Optional parameters: Difference between revisions
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{{task|Basic language learning}}
{{omit from|Rust}}
;Task:
Define a function/method/subroutine which sorts a sequence ("table") of sequences ("rows") of strings ("cells"), by one of the strings. Besides the input to be sorted, it shall have the following optional parameters:
:{|
|
----
; ordering
: A function specifying the ordering of strings; lexicographic by default.
Line 8 ⟶ 13:
; reverse
: Reverses the ordering.
----
|}
This task should be considered to include both positional and named optional parameters, as well as overloading on argument count as in Java or selector name as in Smalltalk, or, in the extreme, using different function names. Provide these variations of sorting '''in whatever way is most natural to your language'''. If the language supports both methods naturally, you are encouraged to describe both.
Do not implement a sorting algorithm; this task is about the interface. If you can't use a built-in sort routine, just omit the implementation (with a comment).
See also:
* [[Named Arguments]]
<br><br>
=={{header|Ada}}==
As described in [[Named_parameters]], all parameters have to be named. You can use positional or keyed association. Optional parameters are the ones with default values.
<syntaxhighlight lang="ada">package Tables is
type Table is private;
type Ordering is (Lexicographic, Psionic, ...); -- add others
procedure Sort (It : in out Table;
Order_By : in Ordering := Lexicographic;
Column : in Positive := 1;
Reverse_Ordering : in Boolean := False);
private
... -- implementation specific
end Tables;</syntaxhighlight>
example of use:
<syntaxhighlight lang="ada">with Tables;
procedure Table_Test is
My_Table : Tables.Table;
begin
... -- insert stuff in table
Sort (My_Table); -- use default sorting
Sort (My_Table, Psionic, 5, True); -- use psionic sorting by 5th column in reverse order
Sort (It => My_Table, Reverse_Ordering => True); -- use default sorting in reverse order
... -- other stuff
end Table_Test;</syntaxhighlight>
=={{header|ALGOL 68}}==
<syntaxhighlight lang="algol68"># as the options have distinct types (INT, BOOL and PROC( STRING, STRING )INT) the #
# easiest way to support these optional parameters in Algol 68 would be to have an array #
# with elements of these types #
# See the Named Arguments sample for cases where the option types are not distinct #
# default comparison function #
PROC default compare = ( STRING a, b )INT: IF a < b THEN -1 ELIF a = b THEN 0 ELSE 1 FI;
# sorting procedure #
PROC configurable sort = ( [,]STRING data, []UNION( INT, BOOL, PROC( STRING, STRING )INT ) options )VOID:
BEGIN
# set initial values for the options #
INT sort column := 2 LWB data;
BOOL reverse sort := FALSE;
PROC( STRING, STRING )INT comparator := default compare;
# overide from the supplied options #
FOR opt pos FROM LWB options TO UPB options DO
CASE options[ opt pos ]
IN ( PROC( STRING, STRING )INT p ): comparator := p
, ( INT c ): sort column := c
, ( BOOL r ): reverse sort := r
ESAC
OD
# do the sort .... #
END # configurable sort # ;
# example calls #
[ 1 : 2, 1 : 3 ]STRING data := ( ( "a", "bb", "cde" ), ( "x", "abcdef", "Q" ) );
# sort data, default comparison, first column, reverse order #
configurable sort( data, ( TRUE ) );
# sort data, second column, ignore first chaacter when sorting, normal order #
configurable sort( data, ( 2, ( STRING a, STRING b )INT: default compare( a[ LWB a + 1 : ], b[ LWB b + 1 : ] ) ) );
# default sort #
configurable sort( data, () )</syntaxhighlight>
=={{header|AppleScript}}==
AppleScript supports named, positional & prepositional parameters, but not default or optional parameters. Though that behavior can be simulated by passing lists or records as the parameter. Handler/functions can be passed as a parameter if they are part of a script object. AppleScript does not have built-in sorting functionality.
<syntaxhighlight lang="applescript">on sortTable(x)
set {sortOrdering, sortColumn, sortReverse} to {sort_lexicographic, 1, false}
try
set sortOrdering to x's ordering
end try
try
set sortColumn to x's column
end try
try
set sortReverse to x's reverse
end try
return sortOrdering's sort(x's sequence, sortColumn, sortReverse)
end sortTable
script sort_lexicographic
on sort(table, column, reverse)
-- Implement lexicographic Sorting process here.
return table
end sort
end script</syntaxhighlight>
Examples of use:
<syntaxhighlight lang="applescript">-- Another sort function.
script sort_colex
on sort(table, column, reverse)
-- Implement colexicographic Sorting process here.
return table
end sort
end script
-- Populate a table (list) with data.
set table to {{1,2},{3,4}}
sortTable({sequence:table, ordering:sort_lexicographic, column:1, reverse:false})
sortTable({sequence:table, ordering:sort_colex, column:2, reverse:true})
sortTable({sequence:table, reverse:true})
sortTable({sequence:table})</syntaxhighlight>
=={{header|Arturo}}==
<syntaxhighlight lang="rebol">sortTable: function [tbl][
column: "0"
reversed?: false
unless null? c: <= attr 'column -> column: to :string c
unless null? attr 'reverse -> reversed?: true
result: new sort.by: column map tbl 'r [
to :dictionary flatten couple 0..dec size r r
]
if reversed? -> reverse 'result
return map result 'r -> values r
]
printTable: function [tbl, title][
print ["==" title]
loop tbl 'row [
print row
]
print ""
]
lst: [
["a", "b", "c"]
["", "q", "z"]
["zap", "zip", "Zot"]
]
printTable sortTable lst "Default sort"
printTable sortTable.column:1 lst "Sorting by column=1"
printTable sortTable.reverse lst "Sorting, reversed"
printTable sortTable.reverse.column:1 lst "Sorting by column=1, reversed"</syntaxhighlight>
{{out}}
<pre>== Default sort
q z
a b c
zap zip Zot
== Sorting by column=1
a b c
q z
zap zip Zot
== Sorting, reversed
zap zip Zot
a b c
q z
== Sorting by column=1, reversed
zap zip Zot
q z
a b c</pre>
=={{header|AutoHotkey}}==
built in support for table sorting is available through the standard Win32 listview.
<
sort_table("Text", column := 2, reverse := 1) ; lexicographic sort
Sleep, 2000
Line 39 ⟶ 214:
Return
; The function supporting named, defaulted arguments
sort_table(ordering = "Text", column = 0, reverse = 0)
{
Line 47 ⟶ 223:
GuiClose:
ExitApp</syntaxhighlight>
=={{header|BASIC}}==
Line 69 ⟶ 244:
570 sort_table a$, 1, 5, 1
</pre>
=={{header|BBC BASIC}}==
BBC BASIC doesn't have optional parameters, but functions can have multiple entry points which take different numbers of parameters, avoiding the need to duplicate code or call a sub-function. Omitted parameters can be declared as LOCAL, which initialises them to zero/false.
<syntaxhighlight lang="bbcbasic"> DIM table$(100,100)
PROCsort_default(table$())
PROCsort_options(table$(), TRUE, 1, FALSE)
END
DEF PROCsort_options(table$(), ordering%, column%, reverse%)
DEF PROCsort_default(table$()) : LOCAL ordering%, column%, reverse%
REM The sort goes here, controlled by the options
REM Zero/FALSE values for the options shall select the defaults
ENDPROC</syntaxhighlight>
=={{header|Bracmat}}==
Bracmat functions always have exactly one parameter, which is references by <code>!arg</code> in the function body. Positional and (optional) named 'parameters' are retrieved from this single parameter <code>!arg</code> by pattern matching. It is a good custom to separate positional parameters by commas or periods and to separate the named parameters by spaces.
<syntaxhighlight lang="bracmat">( ( sortTable
= table ordering column reverse
. !arg
: ( ?table
. ( ? (ordering.?ordering) ?
| ?&lexicographic:?ordering
)
: ( ? (column.?column) ?
| ?&1:?column
)
: ( ? (reverse.?reverse) ?
| ?&no:?reverse
)
)
& (...)
)
& (12.Claes.left)
(11.Otto.right)
(8.Frederikke.middle)
: ?table
& sortTable$(!table.(column.2) (reverse.yes))
);</syntaxhighlight>
=={{header|C}}==
<syntaxhighlight lang="c">#include <stdlib.h>
#include <stdarg.h>
#include <stdio.h>
#include <ctype.h>
#include <string.h>
typedef const char * String;
typedef struct sTable {
String * *rows;
int n_rows,n_cols;
} *Table;
typedef int (*CompareFctn)(String a, String b);
struct {
CompareFctn compare;
int column;
int reversed;
} sortSpec;
int CmprRows( const void *aa, const void *bb)
{
String *rA = *(String *const *)aa;
String *rB = *(String *const *)bb;
int sortCol = sortSpec.column;
String left = sortSpec.reversed ? rB[sortCol] : rA[sortCol];
String right = sortSpec.reversed ? rA[sortCol] : rB[sortCol];
return sortSpec.compare( left, right );
}
/** * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* tbl parameter is a table of rows of strings
* argSpec is a string containing zero or more of the letters o,c,r
* if o is present - the corresponding optional argument is a function which
* determines the ordering of the strings.
* if c is present - the corresponding optional argument is an integer that
* specifies the column to sort on.
* if r is present - the corresponding optional argument is either
* true(nonzero) or false(zero) and if true, the sort will b in reverse order
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
int sortTable(Table tbl, const char* argSpec,... )
{
va_list vl;
const char *p;
int c;
sortSpec.compare = &strcmp;
sortSpec.column = 0;
sortSpec.reversed = 0;
va_start(vl, argSpec);
if (argSpec)
for (p=argSpec; *p; p++) {
switch (*p) {
case 'o':
sortSpec.compare = va_arg(vl,CompareFctn);
break;
case 'c':
c = va_arg(vl,int);
if ( 0<=c && c<tbl->n_cols)
sortSpec.column = c;
break;
case 'r':
sortSpec.reversed = (0!=va_arg(vl,int));
break;
}
}
va_end(vl);
qsort( tbl->rows, tbl->n_rows, sizeof(String *), CmprRows);
return 0;
}
void printTable( Table tbl, FILE *fout, const char *colFmts[])
{
int row, col;
for (row=0; row<tbl->n_rows; row++) {
fprintf(fout, " ");
for(col=0; col<tbl->n_cols; col++) {
fprintf(fout, colFmts[col], tbl->rows[row][col]);
}
fprintf(fout, "\n");
}
fprintf(fout, "\n");
}
int ord(char v)
{
return v-'0';
}
/* an alternative comparison function */
int cmprStrgs(String s1, String s2)
{
const char *p1 = s1;
const char *p2 = s2;
const char *mrk1, *mrk2;
while ((tolower(*p1) == tolower(*p2)) && *p1) {
p1++; p2++;
}
if (isdigit(*p1) && isdigit(*p2)) {
long v1, v2;
if ((*p1 == '0') ||(*p2 == '0')) {
while (p1 > s1) {
p1--; p2--;
if (*p1 != '0') break;
}
if (!isdigit(*p1)) {
p1++; p2++;
}
}
mrk1 = p1; mrk2 = p2;
v1 = 0;
while(isdigit(*p1)) {
v1 = 10*v1+ord(*p1);
p1++;
}
v2 = 0;
while(isdigit(*p2)) {
v2 = 10*v2+ord(*p2);
p2++;
}
if (v1 == v2)
return(p2-mrk2)-(p1-mrk1);
return v1 - v2;
}
if (tolower(*p1) != tolower(*p2))
return (tolower(*p1) - tolower(*p2));
for(p1=s1, p2=s2; (*p1 == *p2) && *p1; p1++, p2++);
return (*p1 -*p2);
}
int main()
{
const char *colFmts[] = {" %-5.5s"," %-5.5s"," %-9.9s"};
String r1[] = { "a101", "red", "Java" };
String r2[] = { "ab40", "gren", "Smalltalk" };
String r3[] = { "ab9", "blue", "Fortran" };
String r4[] = { "ab09", "ylow", "Python" };
String r5[] = { "ab1a", "blak", "Factor" };
String r6[] = { "ab1b", "brwn", "C Sharp" };
String r7[] = { "Ab1b", "pink", "Ruby" };
String r8[] = { "ab1", "orng", "Scheme" };
String *rows[] = { r1, r2, r3, r4, r5, r6, r7, r8 };
struct sTable table;
table.rows = rows;
table.n_rows = 8;
table.n_cols = 3;
sortTable(&table, "");
printf("sort on col 0, ascending\n");
printTable(&table, stdout, colFmts);
sortTable(&table, "ro", 1, &cmprStrgs);
printf("sort on col 0, reverse.special\n");
printTable(&table, stdout, colFmts);
sortTable(&table, "c", 1);
printf("sort on col 1, ascending\n");
printTable(&table, stdout, colFmts);
sortTable(&table, "cr", 2, 1);
printf("sort on col 2, reverse\n");
printTable(&table, stdout, colFmts);
return 0;
}</syntaxhighlight>
=={{header|C++}}==
This implementation only accepts function pointers for the comparators, and does not accept function objects, for simplicity.
<syntaxhighlight lang="cpp">#include <vector>
#include <algorithm>
#include <string>
// helper comparator that is passed to std::sort()
template <class T>
struct sort_table_functor {
typedef bool (*CompFun)(const T &, const T &);
const CompFun ordering;
const int column;
const bool reverse;
sort_table_functor(CompFun o, int c, bool r) :
ordering(o), column(c), reverse(r) { }
bool operator()(const std::vector<T> &x, const std::vector<T> &y) const {
const T &a = x[column],
&b = y[column];
return reverse ? ordering(b, a)
: ordering(a, b);
}
};
// natural-order less-than comparator
template <class T>
bool myLess(const T &x, const T &y) { return x < y; }
// this is the function we call, which takes optional parameters
template <class T>
void sort_table(std::vector<std::vector<T> > &table,
int column = 0, bool reverse = false,
bool (*ordering)(const T &, const T &) = myLess) {
std::sort(table.begin(), table.end(),
sort_table_functor<T>(ordering, column, reverse));
}
#include <iostream>
// helper function to print our 3x3 matrix
template <class T>
void print_matrix(std::vector<std::vector<T> > &data) {
for () {
for (int j = 0; j < 3; j++)
std::cout << data[i][j] << "\t";
std::cout << std::endl;
}
}
// order in descending length
bool desc_len_comparator(const std::string &x, const std::string &y) {
return x.length() > y.length();
}
int main() {
std::string data_array[3][3] =
{
{"a", "b", "c"},
{"", "q", "z"},
{"zap", "zip", "Zot"}
};
std::vector<std::vector<std::string> > data_orig;
for (int i = 0; i < 3; i++) {
std::vector<std::string> row;
for (int j = 0; j < 3; j++)
row.push_back(data_array[i][j]);
data_orig.push_back(row);
}
print_matrix(data_orig);
std::vector<std::vector<std::string> > data = data_orig;
sort_table(data);
print_matrix(data);
data = data_orig;
sort_table(data, 2);
print_matrix(data);
data = data_orig;
sort_table(data, 1);
print_matrix(data);
data = data_orig;
sort_table(data, 1, true);
print_matrix(data);
data = data_orig;
sort_table(data, 0, false, desc_len_comparator);
print_matrix(data);
return 0;
}</syntaxhighlight>
=={{header|Clojure}}==
There is a built-in sort routine, but rather than figure out what all these arguments are supposed to mean, I've just defined the interface.
<syntaxhighlight lang="clojure">(defn sort [table & {:keys [ordering column reverse?]
:or {ordering :lex, column 1}}]
(println table ordering column reverse?))
(sort [1 8 3] :reverse? true)
[1 8 3] :lex 1 true</syntaxhighlight>
=={{header|Common Lisp}}==
Common Lisp has both named and positional parameters. The following example shows optional named parameters, using the <code>&key</code> keyword. Optional positional parameters are specified using the <code>&optional</code> keyword.
<syntaxhighlight lang="lisp">(defun sort-table (table &key (ordering #'string<)
(column 0)
reverse)
Line 81 ⟶ 566:
(complement ordering)
ordering)
:key (lambda (row) (elt row column))))</
(Notes: The builtin [http://www.lispworks.com/documentation/HyperSpec/Body/f_sort_.htm sort] takes a "less than" predicate function. The [http://www.lispworks.com/documentation/HyperSpec/Body/f_comple.htm complement] function inverts a predicate.)
Example uses:
<
*DATA*
Line 102 ⟶ 587:
CL-USER> (sort-table *data* :ordering (lambda (a b) (> (length a) (length b))))
(("zap" "zip" "Zot") ("a" "b" "c") ("" "q" "z"))</
=={{header|D}}==
{{trans|Python}}
<syntaxhighlight lang="d">import std.stdio, std.algorithm, std.functional;
string[][] sortTable(string[][] table,
in bool function(string[],string[]) ordering=null,
in int column = 0,
in bool reverse = false) {
if (ordering is null)
table.schwartzSort!(row => row[column])();
else
table.sort!ordering();
if (reverse)
table.reverse();
return table;
}
void main() {
auto data = [["a", "b", "c"],
["", "q", "z"],
["zap", "zip", "Zot"]];
alias show = curry!(writefln, "%-(%s\n%)\n");
show(data);
show(sortTable(data));
show(sortTable(data, null, 2));
show(sortTable(data, null, 1));
show(sortTable(data, null, 1, true));
show(sortTable(data, (a,b) => b.length > a.length));
}</syntaxhighlight>
{{out}}
<pre>["a", "b", "c"]
["", "q", "z"]
["zap", "zip", "Zot"]
["", "q", "z"]
["a", "b", "c"]
["zap", "zip", "Zot"]
["zap", "zip", "Zot"]
["a", "b", "c"]
["", "q", "z"]
["a", "b", "c"]
["", "q", "z"]
["zap", "zip", "Zot"]
["zap", "zip", "Zot"]
["", "q", "z"]
["a", "b", "c"]
["zap", "zip", "Zot"]
["", "q", "z"]
["a", "b", "c"]
</pre>
Another way to emulate optional arguments is with function overloading, creating several functions with a different number of arguments.
=={{header|Delphi}}==
{{libheader| System.SysUtils}}
{{Trans|D}}
<syntaxhighlight lang="delphi">program Optional_parameters;
{$APPTYPE CONSOLE}
uses
System.SysUtils;
type
TRow = TArray<string>;
TOrderingFun = TFunc<TRow, TRow, Boolean>;
TTable = array of TRow;
TRowHelper = record helper for TRow
public
procedure Swap(var other: TRow);
function ToString: string;
function Length: Integer;
end;
TTableHelper = record helper for TTable
private
procedure ExchangeRow(i, j: Integer);
public
procedure Sort(OrderingFun: TOrderingFun);
procedure Reverse;
function ToString: string;
end;
function Max(a, b: Integer): Integer;
begin
if a > b then
exit(a);
Result := b;
end;
{ TRowHelper }
function TRowHelper.Length: Integer;
begin
Result := System.Length(self);
end;
procedure TRowHelper.Swap(var other: TRow);
var
aLengthOther, aLengthSelf, aLength: Integer;
tmp: string;
i: Integer;
begin
aLengthOther := other.Length;
aLengthSelf := self.Length;
aLength := max(aLengthOther, aLengthSelf);
if aLength = 0 then
exit;
SetLength(self, aLength);
SetLength(other, aLength);
for i := 0 to aLength - 1 do
begin
tmp := self[i];
self[i] := other[i];
other[i] := tmp;
end;
SetLength(self, aLengthOther);
SetLength(other, aLengthSelf);
end;
function TRowHelper.ToString: string;
var
i: Integer;
begin
Result := '[';
for i := 0 to High(self) do
begin
if i > 0 then
Result := Result + ', ';
Result := Result + '"' + self[i] + '"';
end;
Result := Result + ']';
end;
{ TTableHelper }
procedure TTableHelper.ExchangeRow(i, j: Integer);
begin
Self[i].Swap(self[j]);
end;
procedure TTableHelper.reverse;
var
aLength, aHalfLength: Integer;
i: Integer;
begin
aLength := Length(self);
aHalfLength := aLength div 2;
for i := 0 to aHalfLength - 1 do
ExchangeRow(i, aLength - i - 1);
end;
procedure TTableHelper.Sort(OrderingFun: TOrderingFun);
var
i, j, aLength: Integer;
begin
if not Assigned(OrderingFun) then
exit;
aLength := Length(self);
for i := 0 to aLength - 2 do
for j := i + 1 to aLength - 1 do
if OrderingFun(self[i], self[j]) then
ExchangeRow(i, j);
end;
function TTableHelper.ToString: string;
var
i: Integer;
begin
Result := '[';
for i := 0 to High(self) do
begin
if i > 0 then
Result := Result + #10;
Result := Result + self[i].ToString;
end;
Result := Result + ']';
end;
function SortTable(table: TTable; Ordering: TOrderingFun = nil; column: Integer
= 0; reverse: Boolean = false): TTable;
var
acolumn: Integer;
begin
acolumn := column;
if not Assigned(Ordering) then
Ordering :=
function(left, right: TRow): Boolean
begin
Result := left[acolumn] > right[acolumn];
end;
table.Sort(Ordering);
if (reverse) then
table.reverse();
Result := table;
end;
var
data: TTable = [['a', 'b', 'c'], ['', 'q', 'z'], ['zap', 'zip', 'Zot']];
begin
Writeln(data.ToString, #10);
Writeln(SortTable(data).ToString, #10);
Writeln(SortTable(data).ToString, #10);
Writeln(SortTable(data, nil, 2).ToString, #10);
Writeln(SortTable(data, nil, 1).ToString, #10);
Writeln(SortTable(data, nil, 1, True).ToString, #10);
Writeln(SortTable(data,
function(left, right: TRow): Boolean
begin
Result := left.Length > right.Length;
end).ToString, #10);
Readln;
end.</syntaxhighlight>
{{out}}
<pre>
[["a", "b", "c"]
["", "q", "z"]
["zap", "zip", "Zot"]]
[["", "q", "z"]
["a", "b", "c"]
["zap", "zip", "Zot"]]
[["", "q", "z"]
["a", "b", "c"]
["zap", "zip", "Zot"]]
[["zap", "zip", "Zot"]
["a", "b", "c"]
["", "q", "z"]]
[["a", "b", "c"]
["", "q", "z"]
["zap", "zip", "Zot"]]
[["zap", "zip", "Zot"]
["", "q", "z"]
["a", "b", "c"]]
[["zap", "zip", "Zot"]
["", "q", "z"]
["a", "b", "c"]]</pre>
=={{header|E}}==
In E, as in Java and Smalltalk, optional parameters are defined as different methods with the same base name. Methods are distinguished by name (''verb'') and number of parameters (''arity'').
<syntaxhighlight lang="e">def defaultOrdering(a, b) { return a.op__cmp(b) }
def sort {
to run(table) {
return sort(table, 0, false, defaultOrdering)
}
to run(table, column) {
return sort(table, column, false, defaultOrdering)
}
to run(table, column, reverse) {
return sort(table, column, reverse, defaultOrdering)
}
to run(table :List[List[String]], column :int, reverse :boolean, ordering) {
return table.sort(fn a, b {
def ord := ordering(a[column], b[column])
if (reverse) { -ord } else { ord }
})
}
}</syntaxhighlight>
Named parameters are not builtin, but map-patterns may be used as a substitute. (TODO: Example of this) [[Category:E examples needing attention]]
=={{header|Ecstasy}}==
<syntaxhighlight lang="java">
module OptionalParameters {
typedef Type<String >.Orderer as ColumnOrderer;
typedef Type<String[]>.Orderer as RowOrderer;
static String[][] sort(String[][] table,
ColumnOrderer? orderer = Null,
Int column = 0,
Boolean reverse = False,
) {
// provide a default orderer
orderer ?:= (s1, s2) -> s1 <=> s2;
// optionally reverse the order
ColumnOrderer byString = reverse
? ((s1, s2) -> orderer(s1, s2).reversed)
: orderer;
// sort the indicated column
RowOrderer byColumn = (row1, row2) -> byString(row1[column], row2[column]);
return table.sorted(byColumn);
}
void run() {
String[][] table =
[
["c", "x", "i"],
["a", "y", "p"],
["b", "z", "a"],
];
show("original input", table);
show("by default sort on column 0", sort(table));
show("by column 2", sort(table, column=2));
show("by column 2 reversed", sort(table, column=2, reverse=True));
}
void show(String title, String[][] table) {
@Inject Console console;
console.print($"{title}:");
for (val row : table) {
console.print($" {row}");
}
console.print();
}
}
</syntaxhighlight>
{{out}}
<pre>
original input:
[c, x, i]
[a, y, p]
[b, z, a]
by default sort on column 0:
[a, y, p]
[b, z, a]
[c, x, i]
by column 2:
[b, z, a]
[c, x, i]
[a, y, p]
by column 2 reversed:
[a, y, p]
[c, x, i]
[b, z, a]
</pre>
=={{header|Elixir}}==
{{trans|Ruby}}
<syntaxhighlight lang="elixir">defmodule Optional_parameters do
def sort( table, options\\[] ) do
options = options ++ [ ordering: :lexicographic, column: 0, reverse: false ]
ordering = options[ :ordering ]
column = options[ :column ]
reverse = options[ :reverse ]
sorted = sort( table, ordering, column )
if reverse, do: Enum.reverse( sorted ), else: sorted
end
defp sort( table, :lexicographic, column ) do
Enum.sort_by( table, &elem( &1, column ) )
end
defp sort( table, :numeric, column ) do
Enum.sort_by( table, &elem( &1, column ) |> String.to_integer )
end
def task do
table = [ { "123", "456", "0789" },
{ "456", "0789", "123" },
{ "0789", "123", "456" } ]
IO.write "sort defaults "; IO.inspect sort( table )
IO.write " & reverse "; IO.inspect sort( table, reverse: true )
IO.write "sort column 2 "; IO.inspect sort( table, column: 2)
IO.write " & reverse "; IO.inspect sort( table, column: 2, reverse: true)
IO.write "sort numeric "; IO.inspect sort( table, ordering: :numeric)
IO.write " & reverse "; IO.inspect sort( table, ordering: :numeric, reverse: true)
end
end
Optional_parameters.task</syntaxhighlight>
{{out}}
<pre>
sort defaults [{"0789", "123", "456"}, {"123", "456", "0789"}, {"456", "0789", "123"}]
& reverse [{"456", "0789", "123"}, {"123", "456", "0789"}, {"0789", "123", "456"}]
sort column 2 [{"123", "456", "0789"}, {"456", "0789", "123"}, {"0789", "123", "456"}]
& reverse [{"0789", "123", "456"}, {"456", "0789", "123"}, {"123", "456", "0789"}]
sort numeric [{"123", "456", "0789"}, {"456", "0789", "123"}, {"0789", "123", "456"}]
& reverse [{"0789", "123", "456"}, {"456", "0789", "123"}, {"123", "456", "0789"}]
</pre>
=={{header|Erlang}}==
<syntaxhighlight lang="erlang">
-module( optional_parameters ).
-export( [sort/2, task/0] ).
sort( Table, Options ) ->
Ordering = proplists:get_value( ordering, Options, lexicographic ),
Column = proplists:get_value( column, Options, 1 ),
Is_reverse = proplists:get_value( reverse, Options, false ),
Sorted = sort( Table, Ordering, Column ),
sorted_reverse( Is_reverse, Sorted ).
task() ->
io:fwrite( "sort defaults ~p~n", [sort( table(), [])] ),
io:fwrite( "reverse ~p~n", [sort( table(), [reverse])] ),
io:fwrite( "sort column 3 ~p~n", [sort( table(), [{column, 3}])] ),
io:fwrite( "reverse ~p~n", [sort( table(), [{column, 3}, reverse])] ),
io:fwrite( "sort numeric ~p~n", [sort( table(), [{ordering, numeric}])] ),
io:fwrite( "reverse ~p~n", [sort( table(), [{ordering, numeric}, reverse])] ).
row_numeric( Tuple ) -> erlang:list_to_tuple( [{erlang:list_to_integer(X), X} || X <- erlang:tuple_to_list(Tuple)] ).
row_remove_numeric( Tuple ) -> erlang:list_to_tuple( [Y || {_X, Y} <- erlang:tuple_to_list(Tuple)] ).
sort( Table, lexicographic, Column ) -> lists:keysort( Column, Table );
sort( Table, numeric, Column ) ->
Numeric_table = [row_numeric(X) || X <- Table],
Sorted_numeric = lists:keysort( Column, Numeric_table ),
[row_remove_numeric(X) || X <- Sorted_numeric].
sorted_reverse( true, Sorted ) -> lists:reverse( Sorted );
sorted_reverse( false, Sorted ) -> Sorted.
table() -> [table_row1(), table_row2(), table_row3()].
table_row1() -> {"123", "456", "0789"}.
table_row2() -> {"456", "0789", "123"}.
table_row3() -> {"0789", "123", "456"}.
</syntaxhighlight>
{{out}}
<pre>
23> optional_parameters:task().
sort defaults [{"0789","123","456"},{"123","456","0789"},{"456","0789","123"}]
reverse [{"456","0789","123"},{"123","456","0789"},{"0789","123","456"}]
sort column 3 [{"123","456","0789"},{"456","0789","123"},{"0789","123","456"}]
reverse [{"0789","123","456"},{"456","0789","123"},{"123","456","0789"}]
sort numeric [{"123","456","0789"},{"456","0789","123"},{"0789","123","456"}]
reverse [{"0789","123","456"},{"456","0789","123"},{"123","456","0789"}]
</pre>
=={{header|F_Sharp|F#}}==
{{trans|Oz}}
F# supports optional parameters for members only, not for free-standing functions.
Optional parameters are marked by using a question mark in front of the identifier. Their values are passed as option types, i.e. as <code>Some value</code> or <code>None</code>. The helper function <code>defaultArg</code> can be used to specify default values. In the example below, we use shadowing in order to reuse the identifiers <code>ordering</code>, <code>column</code> and <code>reverse</code>.
Typically, parameters are named at the caller site when optional parameters are involved. However, this is not technically required as long as only right-most arguments are omitted.
<syntaxhighlight lang="fsharp">type Table(rows:string[][]) =
// in-place sorting of rows
member x.Sort(?ordering, ?column, ?reverse) =
let ordering = defaultArg ordering compare
let column = defaultArg column 0
let reverse = defaultArg reverse false
let factor = if reverse then -1 else 1
let comparer (row1:string[]) (row2:string[]) =
factor * ordering row1.[column] row2.[column]
Array.sortInPlaceWith comparer rows
member x.Print() =
for row in rows do printfn "%A" row
// Example usage
let t = new Table([| [|"a"; "b"; "c"|]
[|""; "q"; "z"|]
[|"can"; "z"; "a"|] |])
printfn "Unsorted"; t.Print()
t.Sort()
printfn "Default sort"; t.Print()
t.Sort(column=2)
printfn "Sorted by col. 2"; t.Print()
t.Sort(column=1)
printfn "Sorted by col. 1"; t.Print()
t.Sort(column=1, reverse=true)
printfn "Reverse sorted by col. 1"; t.Print()
t.Sort(ordering=fun s1 s2 -> compare s2.Length s1.Length)
printfn "Sorted by decreasing length"; t.Print()</syntaxhighlight>
Output:
<pre>Unsorted
[|"a"; "b"; "c"|]
[|""; "q"; "z"|]
[|"can"; "z"; "a"|]
Default sort
[|""; "q"; "z"|]
[|"a"; "b"; "c"|]
[|"can"; "z"; "a"|]
Sorted by col. 2
[|"can"; "z"; "a"|]
[|"a"; "b"; "c"|]
[|""; "q"; "z"|]
Sorted by col. 1
[|"a"; "b"; "c"|]
[|""; "q"; "z"|]
[|"can"; "z"; "a"|]
Reverse sorted by col. 1
[|"can"; "z"; "a"|]
[|""; "q"; "z"|]
[|"a"; "b"; "c"|]
Sorted by decreasing length
[|"can"; "z"; "a"|]
[|"a"; "b"; "c"|]
[|""; "q"; "z"|]</pre>
=={{header|Factor}}==
Factor doesn't have special support for optional parameters, so the idiom is to define a tuple with desired initial values, set the desired slots, then pass it to a word.
<syntaxhighlight lang="factor">USING: accessors combinators io kernel math.order prettyprint
sequences sorting ;
TUPLE: table-sorter
data
{ column initial: 0 }
reversed?
{ ordering initial: [ ] } ;
: <table-sorter> ( -- obj ) table-sorter new ;
: sort-table ( table-sorter -- matrix )
{
[ data>> ]
[ column>> [ swap nth ] curry ]
[ ordering>> compose ]
[ reversed?>> [ >=< ] [ <=> ] ? [ bi@ ] prepose curry ]
} cleave [ sort ] curry call( x -- x ) ;
! ===== Now we can use the interface defined above =====
CONSTANT: table
{ { "a" "b" "c" } { "" "q" "z" } { "can" "z" "a" } }
"Unsorted" print
table simple-table.
"Default sort" print
<table-sorter>
table >>data
sort-table simple-table.
"Sorted by col 2" print
<table-sorter>
table >>data
2 >>column
sort-table simple-table.
"Sorted by col 1" print
<table-sorter>
table >>data
1 >>column
sort-table simple-table.
"Reverse sorted by col 1" print
<table-sorter>
table >>data
1 >>column
t >>reversed?
sort-table simple-table.
"Sorted by decreasing length" print
<table-sorter>
table >>data
t >>reversed?
[ length ] >>ordering
sort-table simple-table.</syntaxhighlight>
{{out}}
<pre>
Unsorted
a b c
q z
can z a
Default sort
q z
a b c
can z a
Sorted by col 2
can z a
a b c
q z
Sorted by col 1
a b c
q z
can z a
Reverse sorted by col 1
can z a
q z
a b c
Sorted by decreasing length
can z a
a b c
q z
</pre>
=={{header|Fortran}}==
Line 109 ⟶ 1,209:
In Fortran, each argument has its "name". The <tt>optional</tt> attribute can be used to specify that an argument is optional, and its presence (or absence) can be tested using the <tt>present</tt> intrinsic (so that we can give a default value, or execute accordingly a totally different code).
<
! use any module needed for the sort function(s)
! and all the interfaces needed to make the code work
Line 177 ⟶ 1,277:
end subroutine sort_table
end module ExampleOptionalParameter</
<
use ExampleOptionalParameter
implicit none
Line 214 ⟶ 1,314:
call sort_table(table, column=2)
end program UsingTest</
=={{header|FreeBASIC}}==
<syntaxhighlight lang="freebasic">Function power(n As Integer, p As Integer = 2) As Double
Return n ^ p
End Function
Print power(2) ' muestra 4
Print power(2, 3) ' muestra 8
Sleep</syntaxhighlight>
=={{header|Go}}==
Go does not have optional parameters so we list the idiomatic alternatives and some less idiomatic ways of achieving an effect similar to optional parameters.
===Idiomatic (non-solutions)===
'''Zero values'''
The most idiomatic way to write this particular sorting function would be a single function that required all three parameters. Wherever practical in Go, the zero value is used as a default, and that seems meaningful in this situation. Given a table t with method <tt>(table) sort(less func(cell, cell) bool, column int, reverse bool)</tt>, calling <tt>t.sort(nil, 0, false)</tt> to "take the defaults" would make sense. This approach is probably closest to "positional parameters" mentioned in the task description. Note an idiomatic way of specifying an ordering in Go is to provide a "less" function, a function that takes two values and returns true if the the first is "less than" the second in whatever sense specifies the ordering.
'''Struct'''
As the number of optional parameters grows, at some point it can be easier to pass a struct containing all of the "parameters". An advantage with this is that you can write a constructor function that sets defaults other than zero values. This is also idiomatic.
Here is a partial example, partial because it doesn't really have the feel yet of "optional parameters." Note the call to do the reverse sort takes three lines of code, one to construct the parameter struct, one to set the option, and one more to make the call.
<syntaxhighlight lang="go">type cell string
type spec struct {
less func(cell, cell) bool
column int
reverse bool
}
func newSpec() (s spec) {
// initialize any defaults
return
}
// sort with all defaults
t.sort(newSpec())
// reverse sort
s := newSpec
s.reverse = true
t.sort(s)</syntaxhighlight>
===Struct literal with keyed elements===
A solution providing more the feel of optional parameters is to pass a struct literal. Go allows a
struct literal to be initialized with named fields but does not require all fields to be specified and does not require them to be specified in order. Thus passing a struct literal can provide very much the feel of optional named parameters. Given,
<syntaxhighlight lang="go">type spec struct {
ordering func(cell, cell) bool
column int
reverse bool
}</syntaxhighlight>
the following struct literal fills in zero values for ordering and column and assigns true to the field reverse.
<syntaxhighlight lang="go">spec{reverse: true}</syntaxhighlight>
Structs in Go are values and are copied when passed as parameters. The result of having a single struct parameter is that the three fields are pushed on the stack, just about like they would if they were separate parameters. The effect is named parameters with unmentioned parameters defaulting to their zero value.
While the effect is close to that of optional parameters, Go idioms have evolved to make this technique quite non-idiomatic. The very popular tool <tt>go vet</tt> issues a warning if a struct literal only initializes a partial set of elements. Popular code grading services on the internet run go vet and will give your code a lower grade for using this technique.
Nevertheless, a complete program to demonstrate:
<syntaxhighlight lang="go">package main
import (
"fmt"
"sort"
)
type cell string
type row []cell
type table struct {
rows []row
column int
less func(cell, cell) bool
}
func (c cell) String() string {
return fmt.Sprintf("%q", string(c))
}
func (t table) printRows(heading string) {
fmt.Println("--", heading)
for _, row := range t.rows {
fmt.Println(row)
}
fmt.Println()
}
// sort.Interface
func (t table) Len() int { return len(t.rows) }
func (t table) Swap(i, j int) { t.rows[i], t.rows[j] = t.rows[j], t.rows[i] }
func (t table) Less(i, j int) bool {
return t.less(t.rows[i][t.column], t.rows[j][t.column])
}
// struct implements named parameter-like capability
type spec struct {
ordering func(cell, cell) bool
column int
reverse bool
}
func (t *table) sort(s spec) {
// set up column and comparison function for sort
t.column = s.column
switch {
case s.ordering != nil:
t.less = s.ordering
case s.reverse:
t.less = func(a, b cell) bool { return a > b }
default:
t.less = func(a, b cell) bool { return a < b }
}
// sort
sort.Sort(t)
// reverse if necessary
if s.ordering == nil || !s.reverse {
return
}
last := len(t.rows) - 1
for i := last / 2; i >= 0; i-- {
t.rows[i], t.rows[last-i] = t.rows[last-i], t.rows[i]
}
}
func main() {
t := table{rows: []row{
{"pail", "food"},
{"pillbox", "nurse maids"},
{"suitcase", "airedales"},
{"bathtub", "chocolate"},
{"schooner", "ice cream sodas"},
}}
t.printRows("song")
// no "parameters"
t.sort(spec{})
t.printRows("sorted on first column")
// "named parameter" reverse.
t.sort(spec{reverse: true})
t.printRows("reverse sorted on first column")
// "named parameters" column and ordering
t.sort(spec{
column: 1,
ordering: func(a, b cell) bool { return len(a) > len(b) },
})
t.printRows("sorted by descending string length on second column")
}</syntaxhighlight>
Output:
<pre>
-- song
["pail" "food"]
["pillbox" "nurse maids"]
["suitcase" "airedales"]
["bathtub" "chocolate"]
["schooner" "ice cream sodas"]
-- sorted on first column
["bathtub" "chocolate"]
["pail" "food"]
["pillbox" "nurse maids"]
["schooner" "ice cream sodas"]
["suitcase" "airedales"]
-- reverse sorted on first column
["suitcase" "airedales"]
["schooner" "ice cream sodas"]
["pillbox" "nurse maids"]
["pail" "food"]
["bathtub" "chocolate"]
-- sorted by descending string length on second column
["schooner" "ice cream sodas"]
["pillbox" "nurse maids"]
["suitcase" "airedales"]
["bathtub" "chocolate"]
["pail" "food"]
</pre>
===Functional options===
A technique that gets a nod of approval from the idiom police is sometimes termed "functional options." This technique involves a bit of tricky machinery though and so has not really gained wide popularity. It makes use of Go's variadic arguments and uses functions to initialize a parameter struct. A full solution:
<syntaxhighlight lang="go">package main
import (
"fmt"
"sort"
)
type cell string
type row []cell
type table struct {
rows []row
column int
less func(cell, cell) bool
}
func (c cell) String() string {
return fmt.Sprintf("%q", string(c))
}
func (t table) printRows(heading string) {
fmt.Println("--", heading)
for _, row := range t.rows {
fmt.Println(row)
}
fmt.Println()
}
// sort.Interface
func (t table) Len() int { return len(t.rows) }
func (t table) Swap(i, j int) { t.rows[i], t.rows[j] = t.rows[j], t.rows[i] }
func (t table) Less(i, j int) bool {
return t.less(t.rows[i][t.column], t.rows[j][t.column])
}
// struct implements named parameter-like capability
type spec struct {
ordering func(cell, cell) bool
column int
reverse bool
}
// A defined option type is not really needed by the technique, but has
// a nice advantage for documentation. If this type is exported, then
// the the Go documentation tool go doc will organize all of the option
// functions together under the type. (Go doc will see them as constructors
// for the type.)
type Option func(*spec)
func ordering(o func(cell, cell) bool) Option {
return func(s *spec) { s.ordering = o }
}
func column(c int) Option {
return func(s *spec) { s.column = c }
}
func reverse() Option {
return func(s *spec) { s.reverse = true }
}
func (t *table) sort(options ...Option) {
var s spec
for _, o := range options {
o(&s)
}
// set up column and comparison function for sort
t.column = s.column
switch {
case s.ordering != nil:
t.less = s.ordering
case s.reverse:
t.less = func(a, b cell) bool { return a > b }
default:
t.less = func(a, b cell) bool { return a < b }
}
// sort
sort.Sort(t)
// reverse if necessary
if s.ordering == nil || !s.reverse {
return
}
last := len(t.rows) - 1
for i := last / 2; i >= 0; i-- {
t.rows[i], t.rows[last-i] = t.rows[last-i], t.rows[i]
}
}
func main() {
t := table{rows: []row{
{"pail", "food"},
{"pillbox", "nurse maids"},
{"suitcase", "airedales"},
{"bathtub", "chocolate"},
{"schooner", "ice cream sodas"},
}}
t.printRows("song")
// no parameters
t.sort()
t.printRows("sorted on first column")
// "named parameter" reverse.
t.sort(reverse())
t.printRows("reverse sorted on first column")
// "named parameters" column and ordering
byLen := func(a, b cell) bool { return len(a) > len(b) }
t.sort(column(1), ordering(byLen))
t.printRows("sorted by descending string length on second column")
}</syntaxhighlight>
Output same as previous solution.
=={{header|Groovy}}==
Optional Parameters:
<syntaxhighlight lang="groovy">def orderedSort(Collection table, column = 0, reverse = false, ordering = {x, y -> x <=> y } as Comparator) {
table.sort(false) { x, y -> (reverse ? -1 : 1) * ordering.compare(x[column], y[column])}
}</syntaxhighlight>
Test code:
<syntaxhighlight lang="groovy">def table = [['a', 'b', 'c'], ['', 'q', 'z'], ['zap', 'zip', 'Zot']]
assert orderedSort(table) == [['', 'q', 'z'], ['a', 'b', 'c'], ['zap', 'zip', 'Zot']]
assert orderedSort(table, 2) == [['zap', 'zip', 'Zot'], ['a', 'b', 'c'], ['', 'q', 'z']]
assert orderedSort(table, 1) == [['a', 'b', 'c'], ['', 'q', 'z'], ['zap', 'zip', 'Zot']]
assert orderedSort(table, 1, true) == [['zap', 'zip', 'Zot'],['', 'q', 'z'],['a', 'b', 'c']]
assert orderedSort(table, 0, false, {x, y -> y?.size() <=> x?.size()} as Comparator) == [['zap', 'zip', 'Zot'],['a', 'b', 'c'],['', 'q', 'z']]</syntaxhighlight>
Named Parameters:
<syntaxhighlight lang="groovy">Collection.metaClass.orderedSort = { params ->
def column = params?.column ?: 0
def reverse = params?.reverse ?: false
def ordering = params?.ordering ?: {x, y -> x <=> y } as Comparator
table.sort(false) { x, y -> (reverse ? -1 : 1) * ordering.compare(x[column], y[column])}
}</syntaxhighlight>
Test Code:
<syntaxhighlight lang="groovy">def table = [['a', 'b', 'c'], ['', 'q', 'z'], ['zap', 'zip', 'Zot']]
assert table.orderedSort() == [['', 'q', 'z'], ['a', 'b', 'c'], ['zap', 'zip', 'Zot']]
assert table.orderedSort(column: 2) == [['zap', 'zip', 'Zot'], ['a', 'b', 'c'], ['', 'q', 'z']]
assert table.orderedSort(column: 1) == [['a', 'b', 'c'], ['', 'q', 'z'], ['zap', 'zip', 'Zot']]
assert table.orderedSort(column: 1, reverse: true) == [['zap', 'zip', 'Zot'],['', 'q', 'z'],['a', 'b', 'c']]
assert table.orderedSort(ordering: {x, y -> y?.size() <=> x?.size()} as Comparator) == [['zap', 'zip', 'Zot'],['a', 'b', 'c'],['', 'q', 'z']]</syntaxhighlight>
=={{header|Haskell}}==
Option 1: Using haskell's record update syntax, we can simulate named default arguments. This method has the drawback of not allowing for a parameter to be positional and named simultaneously.
<syntaxhighlight lang="haskell">
{-# LANGUAGE RecordWildCards #-}
data SorterArgs = SorterArgs { cmp :: String, col :: Int, rev :: Bool } deriving Show
defSortArgs = SorterArgs "lex" 0 False
sorter :: SorterArgs -> [[String]] -> [[String]]
sorter (SorterArgs{..}) = case cmp of
_ -> undefined
main = do
sorter defSortArgs{cmp = "foo", col=1, rev=True} [[]]
sorter defSortArgs{cmp = "foo"} [[]]
sorter defSortArgs [[]]
return ()
</syntaxhighlight>
Option 2: This method has the drawback of being a bit verbose and requiring you to supply "Maybe a" arguments.
<syntaxhighlight lang="haskell">
import Data.Maybe (fromMaybe)
-- Use fromMaybe as an operator because its prettier
(//) = flip fromMaybe
sorter :: Maybe String -> Maybe Int -> Maybe Bool -> [[String]] -> [[String]]
sorter ((// "lex") -> cmp)
((// 0) -> col)
((// False) -> rev) = undefined
main = do
sorter (Just "foo") (Just 1) (Just True)
sorter Nothing Nothing Nothing
</syntaxhighlight>
=={{header|Icon}} and {{header|Unicon}}==
Optional named parameters are not the norm in Icon/Unicon. In the example below ''bubblesortf'' would be a version of [[Sorting_algorithms/Bubble_sort#Icon_and_Unicon|Bubble Sort]] modified to sort on a column number (Ordering is already supported). It could equally be replaced by any similarly modified Rosetta sort. The use of ''reverse'' on a list is a Unicon extension; in Icon a procedure from the IPL must be linked.
<syntaxhighlight lang="icon">
procedure main()
X := [ [1,2,3], [2,3,1], [3,1,2]) # A list of lists
Sort(X) # vanilla sort
Sort(X,"ordering","numeric","column",2,"reverse") # using optional parameters
end
procedure Sort(X,A[]) # A[] provides for a variable number of arguments
while a := get(A) do {
case a of {
"ordering" : op := case get(A) | runerr(205,a) of {
"lexicographic"|"string": "<<"
"numeric": "<"
default: runerr(205,op)
}
"column" : col := 0 < integer(col := get(A)) | runerr(205,col)
"reverse" : reverseorder := reverse
default: runerr(205,a)
}
return (\reverseorder|1)(bubblesortf(X,\c|1,\op|"<<")) # reverse or return the sorted list
end</syntaxhighlight>
=={{header|J}}==
<syntaxhighlight lang="j">srtbl=: verb define
'' srtbl y
:
'`ordering column reverse'=. x , (#x)}. ]`0:`0:
|.^:reverse y /: ordering (column {"1 ])y
)</syntaxhighlight>
For simplicity, the optional arguments are all functions, and are positional (on the left -- the table, with its arbitrary number of rows and columns, is on the right). Note also that the ordering function is expected to map its entire argument (since this offers much better efficiencies than a binary comparison).
'''Example Use'''
<syntaxhighlight lang="j"> ]Table=: ('a';'b';'c'),('';'q';'z'),:'zip';'zap';'Zot'
┌───┬───┬───┐
│a │b │c │
├───┼───┼───┤
│ │q │z │
├───┼───┼───┤
│zip│zap│Zot│
└───┴───┴───┘
srtbl Table NB. default sort
┌───┬───┬───┐
│ │q │z │
├───┼───┼───┤
│a │b │c │
├───┼───┼───┤
│zip│zap│Zot│
└───┴───┴───┘
]`1: srtbl Table NB. sort by column 1
┌───┬───┬───┐
│a │b │c │
├───┼───┼───┤
│ │q │z │
├───┼───┼───┤
│zip│zap│Zot│
└───┴───┴───┘
]`2:`1: srtbl Table NB. reverse sort by column 2
┌───┬───┬───┐
│zip│zap│Zot│
├───┼───┼───┤
│ │q │z │
├───┼───┼───┤
│a │b │c │
└───┴───┴───┘
#&>`0: srtbl Table NB. sort by length
┌───┬───┬───┐
│ │q │z │
├───┼───┼───┤
│a │b │c │
├───┼───┼───┤
│zip│zap│Zot│
└───┴───┴───┘</syntaxhighlight>
=={{header|Java}}==
Java has no optional parameters, but methods can be overloaded on the number and types of arguments, which can be used to effectively achieve optional positional parameters.
<syntaxhighlight lang="java">import java.util.*;
public class OptionalParams {
// "natural ordering" comparator
static <T extends Comparable<? super T>> Comparator<T> naturalOrdering() {
return Collections.reverseOrder(Collections.<T>reverseOrder());
}
public static <T extends Comparable<? super T>> void
Line 245 ⟶ 1,791:
sortTable(T[][] table,
int column, boolean reverse) {
sortTable(table, column, reverse,
}
public static <T> void sortTable(T[][] table,
Line 297 ⟶ 1,843:
// prints: [[zap, zip, Zot], [a, b, c], [, q, z]]
}
}</
=={{header|JavaScript}}==
See [[Named parameters#JavaScript]], to pass named parameters one uses an object with properties set:
<syntaxhighlight lang="javascript">function sorter(table, options) {
opts = {}
opts.ordering = options.ordering || 'lexicographic';
opts.column = options.column || 0;
opts.reverse = options.reverse || false;
// ...
}
sorter(the_data, {reverse: true, ordering: 'numeric'});</syntaxhighlight>
=={{header|jq}}==
In jq, there are two approaches to defining optional parameters:
* Using a JSON object to define the parameters;
* Using jq's support for multiple arities (in versions of jq higher than 1.4)
The first approach gives the most flexibility, but it is sometimes
tedious to use unless augmented by the second approach.
The second approach can be used if jq > 1.4 is available and if it
acceptable to define a hierarchy of parameters, so that the first
parameter becomes required if the second is given, and so on. The
strictures of this approach can often be alleviated by using dynamic
typing.
In this section, we will focus on the first approach as that
is supported by all versions of jq, and because it illustrates
an important point - that in jq, the value of a field (or tag) within
an object can be specified as a 0-arity filter, even though functions
are not JSON objects.
'''An aside on jq and JSON objects'''
Since jq objects are JSON objects, it might be surprising that arity-0
filters can be specified as a value within a JSON object. This is
possible because of the way expressions such as {"function": f} are
interpreted by jq. The key to understanding this is that jq functions
are compiled into closures. Here is an example:
<syntaxhighlight lang="jq">def bar: 2 *.;
def foo: {"a": bar};</syntaxhighlight>
The expression <tt>3 | foo.a</tt> evaluates to 6.
'''Preliminaries''':
In accordance with the task description, we will also suppose that
sort_table(ordering; column; reverse) is already defined. To specify the lexicographic
ordering on strings in terms of an arity-0 filter, we define less_than_or_equal/0 as follows:
<syntaxhighlight lang="jq">def less_than_or_equal: .[0] <= .[1];</syntaxhighlight>
'''The Task''':
<syntaxhighlight lang="jq">def sorter(options):
sort_table( if (options|has("ordering")) then options.ordering
else less_than_or_equal
end;
options.column or 0;
options.reverse or false );
# If jq > 1.4 is being used, we may also define:
def sorter: sorter({});</syntaxhighlight>
'''Examples''':
<syntaxhighlight lang="jq">[1,2] | sorter({ "reverse": true, "ordering": less_than_or_equal } )
[1,2] | sorter({ "reverse": true })
# If sorter/0 has also been defined:
[1,2] | sorter</syntaxhighlight>
=={{header|Julia}}==
Julia supports both named and positional optional parameters. We can define both versions at the same time if we want:
<syntaxhighlight lang="julia">sorttable(T; ordering=<, column=1, reverse=false) =
sort(T, by = t -> t[column], lt = reverse ? (a,b) -> ordering(b,a) : ordering)
sorttable(T, ordering=<, column=1, reverse=false) =
sorttable(T, ordering=ordering, column=column, reverse=reverse)</syntaxhighlight>
where the <code>;</code> in the argument list denotes the named-parameter variant, and we have used Julia's built-in higher-order <code>sort</code> function to do the work. Note that we simply pass a comparison function for the ordering, and the built-in <code><</code> operator is actually just a function that (on strings) compares in lexicographic order.
Example output:
<syntaxhighlight lang="julia">julia> data = {["a", "b", "c"], ["", "q", "z"], ["zap", "zip", "Zot"]}
3-element Array{Any,1}:
["a","b","c"]
["","q","z"]
["zap","zip","Zot"]
julia> sorttable(data, column=2, reverse=true) # named arguments
3-element Array{Any,1}:
["zap","zip","Zot"]
["","q","z"]
["a","b","c"]
julia> sorttable(data, >, 2) # the same thing, with positional arguments
3-element Array{Any,1}:
["zap","zip","Zot"]
["","q","z"]
["a","b","c"] </syntaxhighlight>
=={{header|Klingphix}}==
<syntaxhighlight lang="klingphix">include ..\Utilitys.tlhy
:mypower
1 tolist flatten len
1 equal
( [pop drop 2]
[pop pop drop]
) if
power
;
"2 ^2 = " print 2 mypower ?
"2 ^3 = " print ( 2 3 ) mypower ?
"End " input</syntaxhighlight>
=={{header|Kotlin}}==
<syntaxhighlight lang="scala">// version 1.1.51
typealias Table = List<List<String>>
/* Note that if ordering is specified, first two parameters are ignored */
fun Table.sort(
column: Int = 0,
reverse: Boolean = false,
ordering: Comparator<List<String>> =
if (!reverse) compareBy { it[column] }
else compareByDescending { it[column] }
) = this.sortedWith(ordering)
fun Table.print(title: String) {
println(title)
for (i in 0 until this.size) {
for (j in 0 until this[0].size) System.out.print("%-3s ".format(this[i][j]))
println()
}
println()
}
fun main(args: Array<String>) {
val table = listOf(
listOf("a", "b", "c"),
listOf("", "q", "z"),
listOf("zap", "zip", "Zot")
)
table.print("Original:")
val titles = listOf(
"Sorted by col 0:", "Sorted by col 1:", "Sorted by col 2:",
"Reverse sorted by col 0:", "Reverse sorted by col 1:", "Reverse Sorted by col 2"
)
val params = listOf(
0 to false, 1 to false, 2 to false, 0 to true, 1 to true, 2 to true
)
for ((i, title) in titles.withIndex()) {
val table2 = table.sort(params[i].first, params[i].second)
table2.print(title)
}
// using non-default Comparator (case insensitive by col 2, reversed)
val comp: Comparator<List<String>> = compareByDescending { it[2].toLowerCase() }
val table3 = table.sort(ordering = comp)
table3.print("Reverse case insensitive sort by col 2:")
}</syntaxhighlight>
{{out}}
<pre>
Original:
a b c
q z
zap zip Zot
Sorted by col 0:
q z
a b c
zap zip Zot
Sorted by col 1:
a b c
q z
zap zip Zot
Sorted by col 2:
zap zip Zot
a b c
q z
Reverse sorted by col 0:
zap zip Zot
a b c
q z
Reverse sorted by col 1:
zap zip Zot
q z
a b c
Reverse Sorted by col 2
q z
a b c
zap zip Zot
Reverse case insensitive sort by col 2:
zap zip Zot
q z
a b c
</pre>
=={{header|Lasso}}==
Lasso can handle both positional and named params. Methods support multiple dispatch where each dispatch defines it's own set of parameters.
<syntaxhighlight lang="lasso">define sortarray( // params are set by position
items::array, // required param
ordering::string = 'lexicographic', // optional param
column::integer = 1,
reverse::boolean = false
) => {
// sorting process
local(sorteditems = array)
// Lasso has no build in method to sort an array of arrays by position in the contained arrays
// But a method could be built for it
return #sorteditems
}
define sortarray(
-items::array, // required param
-ordering::string = 'lexicographic', // optional param
-column::integer = 1,
-reverse::boolean = false
) => sortarray(#items, #ordering, #column, #reverse)
local(items = array(
array(10, 'red', 'Volvo'),
array(15, 'gren', 'Ford'),
array(48, 'yellow', 'Kia'),
array(12, 'black', 'Holden'),
array(19, 'brown', 'Fiat'),
array(8, 'pink', 'Batmobile'),
array(74, 'orange', 'Bicycle')
))
sortarray(-items = #items, -reverse)
sortarray(#items)</syntaxhighlight>
=={{header|Logo}}==
{{works with|UCB Logo}}
<syntaxhighlight lang="logo">to sort :table [:column 1] [:ordering "before?] [:reverse "false]
; ...
end</syntaxhighlight>
The function "sort" has a default arity of 1 for the required parameter. When overriding default parameters, you must wrap the call in parentheses to specify the different arity.
<syntaxhighlight lang="logo">sort :table
(sort :table 2)
(sort :table 3 "less? "true)</syntaxhighlight>
=={{header|Lua}}==
<syntaxhighlight lang="lua">
function showTable(tbl)
if type(tbl)=='table' then
local result = {}
for _, val in pairs(tbl) do
table.insert(result, showTable(val))
end
return '{' .. table.concat(result, ', ') .. '}'
else
return (tostring(tbl))
end
end
function sortTable(op)
local tbl = op.table or {}
local column = op.column or 1
local reverse = op.reverse or false
local cmp = op.cmp or (function (a, b) return a < b end)
local compareTables = function (a, b)
local result = cmp(a[column], b[column])
if reverse then return not result else return result end
end
table.sort(tbl, compareTables)
end
A = {{"quail", "deer", "snake"},
{"dalmation", "bear", "fox"},
{"ant", "cougar", "coyote"}}
print('original', showTable(A))
sortTable{table=A}
print('defaults', showTable(A))
sortTable{table=A, column=2}
print('col 2 ', showTable(A))
sortTable{table=A, column=3}
print('col 3 ', showTable(A))
sortTable{table=A, column=3, reverse=true}
print('col 3 rev', showTable(A))
sortTable{table=A, cmp=(function (a, b) return #a < #b end)}
print('by length', showTable(A))
</syntaxhighlight>
{{out}}
<pre>
original {{quail, deer, snake}, {dalmation, bear, fox}, {ant, cougar, coyote}}
defaults {{ant, cougar, coyote}, {dalmation, bear, fox}, {quail, deer, snake}}
col 2 {{dalmation, bear, fox}, {ant, cougar, coyote}, {quail, deer, snake}}
col 3 {{ant, cougar, coyote}, {dalmation, bear, fox}, {quail, deer, snake}}
col 3 rev {{quail, deer, snake}, {dalmation, bear, fox}, {ant, cougar, coyote}}
by length {{ant, cougar, coyote}, {quail, deer, snake}, {dalmation, bear, fox}}
</pre>
=={{header|Maple}}==
<syntaxhighlight lang="maple">
OptionalSort := proc(input, {
ordering :: Or(procedures,identical("lexicographic")) := "lexicographic",
column :: posint := 1,
reverse :: truefalse := false
} )
local compare;
if ordering = "lexicographic" then
compare := (x,y)->evalb(`if`(reverse,x[column]>=y[column],x[column]<=y[column]));
else
compare := (x,y)->`if`(reverse,ordering(x[column],y),ordering(y,x));
end if;
sort( input, compare );
end proc:</syntaxhighlight>
Some examples of this procedure in action:
<syntaxhighlight lang="maple">
> L := [[1, 2], [3, 4], [-5, 7]]:
> OptionalSort(L);
[[-5, 7], [1, 2], [3, 4]]
> OptionalSort(L, reverse);
[[3, 4], [1, 2], [-5, 7]]
> OptionalSort(L, reverse, column = 2);
[[-5, 7], [3, 4], [1, 2]]
</syntaxhighlight>
=={{header|Mathematica}}/{{header|Wolfram Language}}==
<syntaxhighlight lang="mathematica">Options[OptionalSort]={ordering->lexicographic,column->1,reverse-> False};
OptionalSort[x_List,OptionsPattern[]]:=If[OptionValue[reverse]==True,
SortBy[x ,#[[OptionValue[column]]]&]//Reverse,
SortBy[x,#[[OptionValue[column]]]&] ]
OptionalSort[{{"a" ,"b", "c"}, {"", "q", "z"},{"zap" ,"zip", "Zot"}} ]
->{{,q,z},{a,b,c},{zap,zip,Zot}}
OptionalSort[{{"a" ,"b", "c"}, {"", "q", "z"},{"zap" ,"zip", "Zot"}},{ordering->lexicographic,column->2,reverse-> True} ]
->{{zap,zip,Zot},{,q,z},{a,b,c}}</syntaxhighlight>
=={{header|Nemerle}}==
It's possible to use either optional parameters or overloading on parameter number (or type). However, it's less code repetition to use optional parameters when possible (unless, of course, the implementation varies drastically with different parameters).
<syntaxhighlight lang="nemerle">Sorter (table : list[list[string]], ordering = "lexicographic", column = 0, reverse = false) : list[list[string]]
{
// implementation goes here
}</syntaxhighlight>
=={{header|Nim}}==
<syntaxhighlight lang="nim">import algorithm, strutils, sugar
proc printTable(a: seq[seq[string]]) =
for row in a:
for x in row: stdout.write x, repeat(' ', 4 - x.len)
echo ""
echo ""
proc sortTable(a: seq[seq[string]], column = 0, reverse = false,
ordering: (proc(a,b: string): int) = system.cmp) : seq[seq[string]] =
let order = if reverse: Descending else: Ascending
result = a
result.sort(proc(x,y:seq[string]):int = ordering(x[column],y[column]), order)
const data = @[@["a", "b", "c"], @["", "q", "z"], @["zap", "zip", "Zot"]]
printTable data
printTable sortTable(data)
printTable sortTable(data, column = 2)
printTable sortTable(data, column = 1)
printTable sortTable(data, column = 1, reverse = true)
printTable sortTable(data, ordering = (a,b) => cmp[int](b.len,a.len))</syntaxhighlight>
Output:
<pre>a b c
q z
zap zip Zot
q z
a b c
zap zip Zot
zap zip Zot
a b c
q z
a b c
q z
zap zip Zot
zap zip Zot
q z
a b c
zap zip Zot
a b c
q z </pre>
=={{header|Objective-C}}==
Without getting into any detail, here is one way you might implement optional arguments. (Note that since Objective-C is a strict superset of C, any C solution can be used as well.)
<syntaxhighlight lang="objc">typedef enum { kOrdNone, kOrdLex, kOrdByAddress, kOrdNumeric } SortOrder;
@interface MyArray : NSObject {}
// . . .
@end
@implementation MyArray
- (void)sort {
[self sortWithOrdering:kOrdLex onColumn:0 reversed:NO];
}
- (void)sortWithOrdering:(SortOrder)ord {
[self sortWithOrdering:ord onColumn:0 reversed:NO];
}
- (void)sortWithOrdering:(SortOrder)ord onColumn:(int)col {
[self sortWithOrdering:ord onColumn:col reversed:NO];
}
- (void)sortWithOrdering:(SortOrder)ord onColumn:(int)col reversed:(BOOL)rev {
// . . . Actual sort goes here . . .
}
@end</syntaxhighlight>
=={{header|OCaml}}==
OCaml has optional named parameters. It is conventional to place a non-optional parameter after the optional parameters, because if the optional parameters were at the end, then if you don't provide them, it will just look like a partial application (because OCaml supports [[currying]]), resulting in a function which still expects the optional parameters.
<
let cmp x y = ordering (List.nth x column) (List.nth y column) * (if reverse then -1 else 1) in
List.sort cmp table</
Example uses:
<
val data : string list list =
[["a"; "b"; "c"]; [""; "q"; "z"]; ["zap"; "zip"; "Zot"]]
Line 325 ⟶ 2,300:
# sort_table ~ordering:(fun a b -> compare (String.length b) (String.length a)) data;;
- : string list list =
[["zap"; "zip"; "Zot"]; ["a"; "b"; "c"]; [""; "q"; "z"]]</
OCaml does not support optional positional parameters, because, since OCaml supports currying, it would conflict with partial applications, where you do not provide all the arguments to a function, and it results in a function which expects the remaining arguments.
=={{header|Oz}}==
Oz supports optional parameters only for methods, not for functions.
<syntaxhighlight lang="oz">declare
class Table
attr
rows
meth init(Rows)
rows := Rows
end
meth sort(ordering:O<=Lexicographic column:C<=1 reverse:R<=false)
fun {Predicate Row1 Row2}
Res = {O {Nth Row1 C} {Nth Row2 C}}
in
if R then {Not Res} else Res end
end
in
rows := {Sort @rows Predicate}
end
end
fun {Lexicographic As Bs} %% omitted for brevity
end
T = {New Table init([["a" "b" "c"] ["" "q" "z"] ["zap" "zip" "Zot"]])}
in
{T sort}
{T sort(column:3)}
{T sort(column:2)}
{T sort(column:2 reverse:true)}
{T sort(ordering:fun {$ A B} {Length B} < {Length A} end)}</syntaxhighlight>
=={{header|PARI/GP}}==
As it happens the built-in <code>vecsort()</code> function fulfills all the requirements of this task. In general optional arguments are handled in GP by default values:
<syntaxhighlight lang="parigp">sort(v, ordering=0, column=0, reverse=0)</syntaxhighlight>
while in PARI it is handled by checking for NULL (assuming parser code DG, see 5.7.3 in the User's Guide to the PARI library):
<syntaxhighlight lang="c">/*
GP;install("test_func", "vDG", "test", "path/to/test.gp.so");
*/
void
test_func(GEN x) {
if (x == NULL)
pari_printf("Argument omitted.\n");
else
pari_printf("Argument was: %Ps\n", x);
}</syntaxhighlight>
=={{header|Perl}}==
Perl 5 has no formal parameters, so all function arguments must be processed in the function body.
This function expects its first argument to be a reference to an array of arrays. It interprets any remaining arguments as a hash of optional parameters.
<syntaxhighlight lang="perl">sub sorttable
{my @table = @{shift()};
my %opt =
(ordering => sub {$_[0] cmp $_[1]}, column => 0, reverse => 0, @_);
my $col = $opt{column};
my $func = $opt{ordering};
my @result = sort
{$func->($a->[$col], $b->[$col])}
@table;
return ($opt{reverse} ? [reverse @result] : \@result);}</syntaxhighlight>
An example of use:
<syntaxhighlight lang="perl">my $a = [["a", "b", "c"], ["", "q", "z"], ["zap", "zip", "Zot"]];
foreach (@{sorttable $a, column => 1, reverse => 1})
{foreach (@$_)
{printf "%-5s", $_;}
print "\n";}</syntaxhighlight>
=={{header|Phix}}==
{{libheader|Phix/basics}}
Optional parameters are specified simply by declaring a default value. They must however be grouped on the right.
<!--<syntaxhighlight lang="phix">-->
<span style="color: #008080;">function</span> <span style="color: #000000;">increment</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">inc</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">return</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">+</span><span style="color: #000000;">inc</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
<span style="color: #0000FF;">?</span><span style="color: #000000;">increment</span><span style="color: #0000FF;">(</span><span style="color: #000000;">5</span><span style="color: #0000FF;">)</span> <span style="color: #000080;font-style:italic;">-- shows 6</span>
<span style="color: #0000FF;">?</span><span style="color: #000000;">increment</span><span style="color: #0000FF;">(</span><span style="color: #000000;">5</span><span style="color: #0000FF;">,</span><span style="color: #000000;">2</span><span style="color: #0000FF;">)</span> <span style="color: #000080;font-style:italic;">-- shows 7</span>
<!--</syntaxhighlight>-->
You can also use a variable length sequence to emulate optional parameters.
<!--<syntaxhighlight lang="phix">-->
<span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"%d records sorted in %3.2s\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">records</span><span style="color: #0000FF;">,</span><span style="color: #7060A8;">time</span><span style="color: #0000FF;">()-</span><span style="color: #000000;">t0</span><span style="color: #0000FF;">})</span>
<!--</syntaxhighlight>-->
In other words printf always accepts exactly three arguments, but the third should contain the correct number of
elements to match the number of format specifications in the second argument.
The following incomplete snippet from demo\pGUI\listview.exw shows the basic idea for sorting a table by any column, up or down:
<!--<syntaxhighlight lang="phix">-->
<span style="color: #004080;">integer</span> <span style="color: #000000;">sortcol</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span><span style="color: #0000FF;">,</span>
<span style="color: #000000;">sortdir</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">1</span>
<span style="color: #008080;">function</span> <span style="color: #000000;">by_column</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">j</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">return</span> <span style="color: #000000;">sortdir</span><span style="color: #0000FF;">*</span><span style="color: #7060A8;">compare</span><span style="color: #0000FF;">(</span><span style="color: #000000;">data</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">][</span><span style="color: #000000;">sortcol</span><span style="color: #0000FF;">],</span><span style="color: #000000;">data</span><span style="color: #0000FF;">[</span><span style="color: #000000;">j</span><span style="color: #0000FF;">][</span><span style="color: #000000;">sortcol</span><span style="color: #0000FF;">])</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">tags</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">tagset</span><span style="color: #0000FF;">(</span><span style="color: #000000;">table_size</span><span style="color: #0000FF;">)</span> <span style="color: #000080;font-style:italic;">-- {1,2,..table_size}</span>
<span style="color: #008080;">function</span> <span style="color: #000000;">click_cb</span><span style="color: #0000FF;">(</span><span style="color: #004080;">Ihandle</span> <span style="color: #000000;">self</span><span style="color: #0000FF;">,</span> <span style="color: #004080;">integer</span> <span style="color: #000000;">l</span><span style="color: #0000FF;">,</span> <span style="color: #004080;">integer</span> <span style="color: #000000;">c</span><span style="color: #0000FF;">,</span> <span style="color: #004080;">atom</span> <span style="color: #000000;">pStatus</span><span style="color: #0000FF;">)</span>
<span style="color: #0000FF;">...</span>
<span style="color: #004080;">string</span> <span style="color: #000000;">sortc</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">sprintf</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"SORTSIGN%d"</span><span style="color: #0000FF;">,</span><span style="color: #000000;">c</span><span style="color: #0000FF;">)</span>
<span style="color: #000000;">sortdir</span> <span style="color: #0000FF;">=</span> <span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">IupGetAttribute</span><span style="color: #0000FF;">(</span><span style="color: #000000;">self</span><span style="color: #0000FF;">,</span><span style="color: #000000;">sortc</span><span style="color: #0000FF;">)=</span><span style="color: #008000;">"DOWN"</span><span style="color: #0000FF;">?-</span><span style="color: #000000;">1</span><span style="color: #0000FF;">:</span><span style="color: #000000;">1</span><span style="color: #0000FF;">)</span>
<span style="color: #7060A8;">IupSetAttribute</span><span style="color: #0000FF;">(</span><span style="color: #000000;">self</span><span style="color: #0000FF;">,</span><span style="color: #000000;">sortc</span><span style="color: #0000FF;">,</span><span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">sortdir</span><span style="color: #0000FF;">=-</span><span style="color: #000000;">1</span><span style="color: #0000FF;">?</span><span style="color: #008000;">"UP"</span><span style="color: #0000FF;">:</span><span style="color: #008000;">"DOWN"</span><span style="color: #0000FF;">))</span>
<span style="color: #000000;">sortcol</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">c</span>
<span style="color: #000000;">tags</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">custom_sort</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">routine_id</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"by_column"</span><span style="color: #0000FF;">),</span><span style="color: #000000;">tags</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">function</span> <span style="color: #000000;">value_cb</span><span style="color: #0000FF;">(</span><span style="color: #004080;">Ihandle</span> <span style="color: #000080;font-style:italic;">/*self*/</span><span style="color: #0000FF;">,</span> <span style="color: #004080;">integer</span> <span style="color: #000000;">l</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">c</span><span style="color: #0000FF;">)</span>
<span style="color: #000000;">l</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">tags</span><span style="color: #0000FF;">[</span><span style="color: #000000;">l</span><span style="color: #0000FF;">]</span>
<span style="color: #008080;">return</span> <span style="color: #000000;">data</span><span style="color: #0000FF;">[</span><span style="color: #000000;">l</span><span style="color: #0000FF;">][</span><span style="color: #000000;">c</span><span style="color: #0000FF;">]</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
<!--</syntaxhighlight>-->
=={{header|Phixmonti}}==
<syntaxhighlight lang="phixmonti">def mypower
1 tolist flatten len
1 == if
1 get 2
else
2 get swap 1 get rot
endif
power
nip
enddef
"2 ^2 = " print 2 mypower print nl
"2 ^3 = " print 2 3 2 tolist mypower print</syntaxhighlight>
More elegant.
<syntaxhighlight lang="phixmonti">include ..\Utilitys.pmt
def mypower
1 tolist flatten len
1 == if
pop drop 2
else
pop pop drop
endif
power
enddef
"2 ^2: " print 2 mypower ?
"2 ^3: " print ( 2 3 ) mypower ?</syntaxhighlight>
More in line with the task description
<syntaxhighlight lang="phixmonti">include ..\Utilitys.pmt
( ( "a" "b" "c" )
( "" "q" "z" )
( "zap" "zip" "Zot" ) )
def mysort /# column reverse #/
len >ps
tps 0 == if drop ( 1 false ) endif
ps> 1 == if false 0 put endif
pop swap >ps pop drop swap
len for var i
i get
tps extract swap 1 put
i set
endfor
sort
swap if reverse endif
len for var i
i get
pop swap tps put
i set
endfor
ps> drop
enddef
pstack
( ) mysort pstack
( 3 ) mysort pstack
( 2 ) mysort pstack
( 2 true ) mysort pstack
</syntaxhighlight>
{{out}}
<pre>
[[["a", "b", "c"], ["", "q", "z"], ["zap", "zip", "Zot"]]]
[[["", "q", "z"], ["a", "b", "c"], ["zap", "zip", "Zot"]]]
[[["zap", "zip", "Zot"], ["a", "b", "c"], ["", "q", "z"]]]
[[["a", "b", "c"], ["", "q", "z"], ["zap", "zip", "Zot"]]]
[[["zap", "zip", "Zot"], ["", "q", "z"], ["a", "b", "c"]]]
=== Press any key to exit ===</pre>
=={{header|PicoLisp}}==
<syntaxhighlight lang="picolisp">(de sortTable (Tbl . @)
(let (Ordering prog Column 1 Reverse NIL) # Set defaults
(bind (rest) # Bind optional params
(setq Tbl
(by '((L) (Ordering (get L Column)))
sort
Tbl ) )
(if Reverse (flip Tbl) Tbl) ) ) )</syntaxhighlight>
Output:
<pre>(de *Data ("a" "bcdef" "X") (" " "qrst" "z") ("zap" "zip" "Zot"))
: (sortTable *Data)
-> ((" " "qrst" "z") ("a" "bcdef" "X") ("zap" "zip" "Zot"))
: (sortTable *Data '(Reverse . T))
-> (("zap" "zip" "Zot") ("a" "bcdef" "X") (" " "qrst" "z"))
: (sortTable *Data '(Column . 2) '(Ordering . length))
-> (("zap" "zip" "Zot") (" " "qrst" "z") ("a" "bcdef" "X"))
: (sortTable *Data '(Ordering . uppc) '(Column . 3))
-> (("a" "bcdef" "X") (" " "qrst" "z") ("zap" "zip" "Zot"))</pre>
=={{header|Python}}==
Line 333 ⟶ 2,529:
Using a pretty-printer for the table
<
for row in data:
print ' '.join('%-5s' % ('"%s"' % cell) for cell in row)
Line 367 ⟶ 2,563:
"a" "b" "c"
"" "q" "z"
>>>
See the Python entry in [[Named_Arguments#Python|Named Arguments]] for a more comprehensive description of Python function parameters and call arguments.
Note that expression for a default argument of an optional parameter is evaluated only once, when the function definition is executed, and all calls of the function where that parameter is missing will be initialized to point to that same shared object. So, if the default argument value is a mutable object (e.g. list, dict, etc.), then any changes to it will affect what is seen by future calls of the function:
<pre>
>>> def foo(x, lst=[]):
... lst.append(x)
... print lst
...
>>> foo(1)
[1]
>>> foo(2)
[1, 2]
>>> foo(3)
[1, 2, 3]
</pre>
=={{header|R}}==
Optional parameters are given using a name=value syntax within the function header.
<syntaxhighlight lang="r">tablesort <- function(x, ordering="lexicographic", column=1, reverse=false)
{
# Implementation
}
# Usage is e.g.
tablesort(mytable, column=3)</syntaxhighlight>
=={{header|Racket}}==
<syntaxhighlight lang="racket">
#lang racket
(define (sort-table table
[ordering string<=?]
[column 0]
[reverse? #f])
(sort table (if reverse?
(negate ordering)
ordering)
#:key (λ (row) (list-ref row column))))
</syntaxhighlight>
=={{header|Raku}}==
(formerly Perl 6)
Using named parameters:
<syntaxhighlight lang="raku" line>method sorttable(:$column = 0, :$reverse, :&ordering = &infix:<cmp>) {
my @result = self»[$column].sort: &ordering;
return $reverse ?? @result.reverse !! @result;
}</syntaxhighlight>
Using optional positional parameters:
<syntaxhighlight lang="raku" line>method sorttable-pos($column = 0, $reverse?, &ordering = &infix:<cmp>) {
my @result = self»[$column].sort: &ordering;
return $reverse ?? @result.reverse !! @result;
}</syntaxhighlight>
=={{header|REXX}}==
The REXX language allows for default values for positional arguments as well as an easy method to check if a string is part of a parameter.
<br>Also allowed are named parameters.
<br><br>The REXX language doesn't have any native sorting functions, so you have to write your own sorting subroutine.
<syntaxhighlight lang="rexx">sortStrings: procedure expose @. /*the stemmed array is named: @. */
col= 1 /*set some defaults (here and below). */
reverse= 'NO'
order= 'LEXICOGRAPHIC'
arg options /*obtain the options (in uppercase). */
do j=1 for words(options) /*examine all the words (options). */
x= word(options, j)
select
when datatype(x, 'W') then col= x / 1 /*normalize the number. */
when pos('=', x)==0 then order= x /*has it an equal sign? */
otherwise parse var x nam '=' value /*get value.*/
end /*select*/
end /*j*/
/*╔═══════════════════════════════════════════════════════════╗
║ check for errors here: COL isn't a positive integer ···, ║
║ REVERSE value isn't NO or YES, ║
║ ORDER value is recognized ··· ║
╚═══════════════════════════════════════════════════════════╝*/
... main body of string sort here ...
return /*stick a fork in it, we're all done. */</syntaxhighlight>
An example use is:
<syntaxhighlight lang="rexx">/*REXX example uses the SortStrings subroutine with some (passed) optional arguments. */
@.1= 'one'; @.2= "two"; @.3= 'three' /*define an array (@.) of strings here.*/
call sortStrings 'Reverse=no' 3
/*stick a fork in it, we're all done. */</syntaxhighlight>
=={{header|Ruby}}==
Ruby allows default values for positional arguments, but they have disadvantages. In the next example, if you want to pass ''reverse=true'', you must also give values for ''ordering'' and ''column''.
<syntaxhighlight lang="ruby">def table_sort(table, ordering=:<=>, column=0, reverse=false)
# ...</syntaxhighlight>
Ruby 2.0 added keyword arguments to the language. These provide the most natural solution.
{{works with|Ruby|2.0}}
<syntaxhighlight lang="ruby">def table_sort(table, ordering: :<=>, column: 0, reverse: false)
p = ordering.to_proc
if reverse
table.sort {|a, b| p.(b[column], a[column])}
else
table.sort {|a, b| p.(a[column], b[column])}
end
end
# Quick example:
table = [
["Ottowa", "Canada"],
["Washington", "USA"],
["Mexico City", "Mexico"],
]
p table_sort(table, column: 1)</syntaxhighlight>
Older versions of Ruby can fake the effect with a Hash (as detailed in [[Named parameters#Ruby]]). The next example needs Ruby 1.8.7 only because the sort code calls <code>Symbol#to_proc</code>; the passing of parameters would yet work with Ruby older than 1.8.7.
{{works with|Ruby|1.8.7}}
<syntaxhighlight lang="ruby">def table_sort(table, opts = {})
defaults = {:ordering => :<=>, :column => 0, :reverse => false}
opts = defaults.merge(opts)
c = opts[:column]
p = opts[:ordering].to_proc
if opts[:reverse]
table.sort {|a, b| p.call(b[c], a[c])}
else
table.sort {|a, b| p.call(a[c], b[c])}
end
end</syntaxhighlight>
=={{header|Rust}}==
Rust doesn't really have optional parameters.
One way could be to use the <code>Option</code> syntax, but then you still would have to specify the optional parameters in the function calls as <code>None</code>, which would kind of defeat the purpose.
Here we use Rust's "standard way" to have optional parameters, i.e. by using builders instead.
<syntaxhighlight lang="rust">use std::cmp::Ordering;
struct Table {
rows: Vec<Vec<String>>,
ordering_function: fn(&str, &str) -> Ordering,
ordering_column: usize,
reverse: bool,
}
impl Table {
fn new(rows: Vec<Vec<String>>) -> Table {
Table {
rows: rows,
ordering_column: 0,
reverse: false,
ordering_function: |str1, str2| str1.cmp(str2),
}
}
}
impl Table {
fn with_ordering_column(&mut self, ordering_column: usize) -> &mut Table {
self.ordering_column = ordering_column;
self
}
fn with_reverse(&mut self, reverse: bool) -> &mut Table {
self.reverse = reverse;
self
}
fn with_ordering_fun(&mut self, compare: fn(&str, &str) -> Ordering) -> &mut Table {
self.ordering_function = compare;
self
}
fn sort(&mut self) {
let fun = &mut self.ordering_function;
let idx = self.ordering_column;
if self.reverse {
self.rows
.sort_unstable_by(|vec1, vec2| (fun)(&vec1[idx], &vec2[idx]).reverse());
} else {
self.rows
.sort_unstable_by(|vec1, vec2| (fun)(&vec1[idx], &vec2[idx]));
}
}
}
#[cfg(test)]
mod test {
use super::Table;
fn generate_test_table() -> Table {
Table::new(vec![
vec!["0".to_string(), "fff".to_string()],
vec!["2".to_string(), "aab".to_string()],
vec!["1".to_string(), "ccc".to_string()],
])
}
#[test]
fn test_simple_sort() {
let mut table = generate_test_table();
table.sort();
assert_eq!(
table.rows,
vec![
vec!["0".to_string(), "fff".to_string()],
vec!["1".to_string(), "ccc".to_string()],
vec!["2".to_string(), "aab".to_string()],
],
)
}
#[test]
fn test_ordering_column() {
let mut table = generate_test_table();
table.with_ordering_column(1).sort();
assert_eq!(
table.rows,
vec![
vec!["2".to_string(), "aab".to_string()],
vec!["1".to_string(), "ccc".to_string()],
vec!["0".to_string(), "fff".to_string()],
],
)
}
#[test]
fn test_with_reverse() {
let mut table = generate_test_table();
table.with_reverse(true).sort();
assert_eq!(
table.rows,
vec![
vec!["2".to_string(), "aab".to_string()],
vec!["1".to_string(), "ccc".to_string()],
vec!["0".to_string(), "fff".to_string()],
],
)
}
#[test]
fn test_custom_ordering_fun() {
let mut table = generate_test_table();
// Simple ordering function that reverses stuff.
// Should operate like the test before.
table.with_ordering_fun(|x, y| x.cmp(y).reverse()).sort();
assert_eq!(
table.rows,
vec![
vec!["2".to_string(), "aab".to_string()],
vec!["1".to_string(), "ccc".to_string()],
vec!["0".to_string(), "fff".to_string()],
],
)
}
#[test]
fn test_everything_together() {
let mut table = generate_test_table();
// Using the reversing cmp function, then reverse (= don't do anything)
// then sort from column 1.
table
.with_ordering_fun(|x, y| x.cmp(y).reverse())
.with_reverse(true)
.with_ordering_column(1)
.sort();
assert_eq!(
table.rows,
vec![
vec!["2".to_string(), "aab".to_string()],
vec!["1".to_string(), "ccc".to_string()],
vec!["0".to_string(), "fff".to_string()],
],
)
}
}
</syntaxhighlight>
=={{header|Scala}}==
With Scala 2.8 optional and named parameters are build in.
<syntaxhighlight lang="scala"> def sortTable(data: List[List[String]],
ordering: (String, String) => Boolean = (_ < _),
column: Int = 0,
reverse: Boolean = false) = {
val result = data.sortWith((a, b) => ordering(a(column), b(column)))
if (reverse) result.reverse else result
}</syntaxhighlight>
<syntaxhighlight lang="scala">val data=List(List("a","b","c"), List("","q","z"), List("zap","zip","Zot"))
println(data)
//-> List(List(a, b, c), List(, q, z), List(zap, zip, Zot))
println(sortTable(data))
//-> List(List(, q, z), List(a, b, c), List(zap, zip, Zot))
println(sortTable(data, reverse=true))
//-> List(List(zap, zip, Zot), List(a, b, c), List(, q, z))
println(sortTable(data, column=2))
//-> List(List(zap, zip, Zot), List(a, b, c), List(, q, z))
println(sortTable(data, ((a, b)=> b.size<a.size)))
//-> List(List(zap, zip, Zot), List(a, b, c), List(, q, z))</syntaxhighlight>
=={{header|Sidef}}==
<syntaxhighlight lang="ruby">func table_sort(table, ordering: '<=>', column: 0, reverse: false) {
if (reverse) {
table.sort {|a,b| b[column].$ordering(a[column])}
} else {
table.sort {|a,b| a[column].$ordering(b[column])}
}
}
# Quick example:
var table = [
["Ottowa", "Canada"],
["Washington", "USA"],
["Mexico City", "Mexico"],
];
say table_sort(table, column: 1);</syntaxhighlight>
{{out}}
<pre>[["Ottowa", "Canada"], ["Mexico City", "Mexico"], ["Washington", "USA"]]</pre>
Missing the point, we can also create and provide a custom method for sorting to ''ordering'':
<syntaxhighlight lang="ruby">class String {
method my_sort(arg) {
(self.len <=> arg.len) ->
|| (self.lc <=> arg.lc) ->
|| (self <=> arg)
}
}
say table_sort(table, column: 1, ordering: 'my_sort');</syntaxhighlight>
{{out}}
<pre>[["Washington", "USA"], ["Ottowa", "Canada"], ["Mexico City", "Mexico"]]</pre>
=={{header|Slate}}==
In Slate, named optional parameters may be specified in the method signature, but not defaults, so there is a macro <tt>defaultsTo:</tt> for specifying that within the method body at run-time.
<syntaxhighlight lang="slate">s@(Sequence traits) tableSort &column: column &sortBy: sortBlock &reverse: reverse
[
column `defaultsTo: 0.
sortBlock `defaultsTo: [| :a :b | (a lexicographicallyCompare: b) isNegative].
(reverse `defaultsTo: False
s sortBy: [| :a :b | sortBlock applyTo: {a at: column. b at: column}]
].</syntaxhighlight>
=={{header|Swift}}==
<syntaxhighlight lang="swift">enum SortOrder { case kOrdNone, kOrdLex, kOrdByAddress, kOrdNumeric }
func sortTable(table: [[String]], less: (String,String)->Bool = (<), column: Int = 0, reversed: Bool = false) {
// . . . Actual sort goes here . . .
}</syntaxhighlight>
=={{header|Tcl}}==
Tcl supports optional parameters to procedures through two mechanisms. It can either work positionally (through giving default values for arguments) or by using a special last argument called “<code>args</code>” which will collect all the remaining arguments into a list that can be processed by the procedure.
{{works with|Tcl|8.4}}
<syntaxhighlight lang="tcl">proc tablesort {table {ordering ""} {column 0} {reverse 0}} {
set direction [expr {$reverse ? "-decreasing" : "-increasing"}]
if {$ordering ne ""} {
lsort -command $ordering $direction -index $column $table
} else {
lsort $direction -index $column $table
}
}
puts [tablesort $data]
puts [tablesort $data "" 1]
puts [tablesort $data "" 0 1]
puts [tablesort $data {
apply {{a b} {expr {[string length $a]-[string length $b]}}}
}]</syntaxhighlight>
When using the second style, it is often common to use [[Named Arguments]] (and in fact the “<code>lsort</code>” already works very much like this). Note that it is most common to use named arguments that start with a “<code>-</code>”, but we omit them here so that we formally match the requirements of the task.
<br>
{{works with|Tcl|8.5}}
<syntaxhighlight lang="tcl">package require Tcl 8.5; # Only for the list expansion syntax
proc tablesort {table args} {
array set opt {
array set opt $args
set pars [list -index $opt(
if {$opt(
if {$opt(
lsort {*}$pars $table
}
puts [tablesort $data]
puts [tablesort $data column 1]
puts [tablesort $data column 0]
puts [tablesort $data column 0 reverse 1]
puts [tablesort $data ordering {
apply {{a b} {expr {[string length $b]-[string length $a]}}}
}]</syntaxhighlight>
=={{header|TIScript}}==
TIScript allows to define optional parameters with default values:
<syntaxhighlight lang="javascript">function sorter(table, ordering = "lexicographic", column = 0, reverse = false) {
// ...
}
sorter(the_data,"numeric");</syntaxhighlight>
=={{header|UNIX Shell}}==
{{works with|bash|4.2}}
<syntaxhighlight lang="bash">#!/usr/bin/env bash
# sort-args.sh
data() {
cat <<EOF
123 456 0789
456 0789 123
0789 123 456
EOF
}
# sort_table [column NUM | KIND | reverse] ... <INPUT >OUTPUT
# KIND = lexicographical | numeric | human
sort_table() {
local opts='-b'
local column=1
while (( $# > 0 )) ; do
case "$1" in
column|col|c) column=${2?Missing column number} ; shift ;;
lexicographical|lex|l) opts+=' -d' ;;
numeric|num|n) opts+=' -g' ;;
human|hum|h) opts+=' -h' ;;
reverse|rev|r) opts+=' -r' ;;
esac
shift
done
eval "sort $opts -k $column,$column -"
}
echo sort defaults ; data | sort_table
echo sort defaults reverse ; data | sort_table reverse
echo sort column 2 ; data | sort_table col 2
echo sort column 2 reverse ; data | sort_table col 2 reverse
echo sort numeric ; data | sort_table numeric
echo sort numeric reverse ; data | sort_table numeric reverse
</syntaxhighlight>
{{out}}
<pre>
$ ./sort-args.sh
sort defaults
0789 123 456
123 456 0789
456 0789 123
sort defaults reverse
456 0789 123
123 456 0789
0789 123 456
sort column 2
456 0789 123
0789 123 456
123 456 0789
sort column 2 reverse
123 456 0789
0789 123 456
456 0789 123
sort numeric
123 456 0789
456 0789 123
0789 123 456
sort numeric reverse
0789 123 456
456 0789 123
123 456 0789
</pre>
=={{header|Ursala}}==
Because functions in Ursala take only a single argument and the usual
programming style is point free, the most natural way of affecting
named optional function parameters is to parameterize the function by
a record with computed fields. Fields in a record instance can be
associated with descriptive identifiers, listed in any order, and
omitted if their default values are intended.
For this task, a record type <code>ss</code> (for sort specification) is defined
with three fields, <code>ordering</code>, <code>column</code>, and <code>reversed</code>. The <code>ordering</code> field
contains a binary relational predicate, with the lexicographic
relation (<code>lleq</code>) being the default. The <code>column</code> field is a natural number with
a default value of 1, and the <code>reversed</code> field is a boolean with a
default value of false.
The <code>sorter</code> is actually a second order function taking a record of
this type as an argument, and returning a function built to order
that is applicable to a list of data to be sorted.
<syntaxhighlight lang="ursala">#import std
#import nat
ss ::
ordering %fZ ~ordering||lleq!
column %n ~column||1!
reversed %b
sorter = +^(~reversed?/~&x! ~&!,-<+ +^/~ordering ~~+ ~&h++ //skip+ predecessor+ ~column)</syntaxhighlight>
Here is a test program using the function above to sort a table
five different ways, mentioning only the information that differs from the
defaults. The table is stored as a list of lists, with one list for each
row, hence three rows and two columns.
<syntaxhighlight lang="ursala">example_table =
<
<'foo','b '>,
<'barr','a '>,
<'bazzz','c'>>
#cast %sLLL
examples =
<
(sorter ss&) example_table, # default sorting algorithm
(sorter ss[ordering: leql]) example_table, # sort by field lengths but otherwise default
(sorter ss[column: 2]) example_table, # etc.
(sorter ss[reversed: true]) example_table,
(sorter ss[reversed: true,column: 2]) example_table></syntaxhighlight>
In practice, these five functions would have been more conveniently expressed using the
built in sort operator as <code>-<&h</code>, <code>leql-<&h</code>, <code>-<&th</code>, <code>-<x&h</code>, and <code>-<x&th</code>
respectively, but this technique is useful in more complicated applications.
Here is the output showing five different sorts of the table.
<pre><
<<'barr','a '>,<'bazzz','c'>,<'foo','b '>>,
<<'foo','b '>,<'barr','a '>,<'bazzz','c'>>,
<<'barr','a '>,<'foo','b '>,<'bazzz','c'>>,
<<'foo','b '>,<'bazzz','c'>,<'barr','a '>>,
<<'bazzz','c'>,<'foo','b '>,<'barr','a '>>></pre>
=={{header|VBA}}==
<syntaxhighlight lang="vb">Private Sub optional_parameters(theRange As String, _
Optional ordering As Integer = 0, _
Optional column As Integer = 1, _
Optional reverse As Integer = 1)
ActiveSheet.Sort.SortFields.Clear
ActiveSheet.Sort.SortFields.Add _
Key:=Range(theRange).Columns(column), _
SortOn:=SortOnValues, _
Order:=reverse, _
DataOption:=ordering 'the optional parameter ordering and above reverse
With ActiveSheet.Sort
.SetRange Range(theRange)
.Header = xlGuess
.MatchCase = False
.Orientation = xlTopToBottom
.SortMethod = xlPinYin
.Apply
End With
End Sub
Public Sub main()
'Sort the strings in the active sheet in Excel
'Supply the range of cells to be sorted
'Optionally specify ordering, default is 0,
'which is normal sort, text and data separately;
'ordering:=1 treats text as numeric data.
'Optionally specify column number, default is 1
'Optionally specify reverse, default is 1
'which sorts in ascending order.
'Specifying reverse:=2 will sort in descending order.
optional_parameters theRange:="A1:C4", ordering:=1, column:=2, reverse:=1
End Sub</syntaxhighlight>
=={{header|Wren}}==
{{libheader|Wren-sort}}
{{libheader|Wren-seq}}
Wren doesn't support optional parameters as such but does support method overloading by ''arity'' (i.e. number of parameters) which makes it easy to simulate them.
<syntaxhighlight lang="wren">import "./sort" for Cmp, Sort
import "./seq" for Lst
class TableSorter {
// uses 'merge' sort to avoid mutating original table
// column is zero based
static sort(table, ordering, column, reverse) {
if (ordering == null) ordering = Fn.new { |r1, r2| Cmp.string.call(r1[column], r2[column]) }
var sorted = Sort.merge(table, ordering)
if (reverse) Lst.reverse(sorted)
return sorted
}
// overloads to simulate optional parameters
static sort(table) { sort(table, null, 0, false) }
static sort(table, ordering) { sort(table, ordering, 0, false) }
static sort(table, ordering, column) { sort(table, ordering, column, false) }
}
var table = [
["first", "1"],
["second", "2"],
["fourth", "4"],
["fifth", "5"],
["third", "3"]
]
System.print("Original table:")
System.print(table.join("\n"))
System.print("\nAfter lexicographic sort by first column:")
var table2 = TableSorter.sort(table)
System.print(table2.join("\n"))
System.print("\nAfter sorting in length order of first column:")
var ordering = Fn.new { |r1, r2| (r1[0].count - r2[0].count).sign }
table2 = TableSorter.sort(table, ordering)
System.print(table2.join("\n"))
System.print("\nAfter lexicographic sort by second column:")
table2 = TableSorter.sort(table, null, 1)
System.print(table2.join("\n"))
System.print("\nAfter reverse lexicographic sort by second column:")
table2 = TableSorter.sort(table, null, 1, true)
System.print(table2.join("\n"))</syntaxhighlight>
{{out}}
<pre>
Original table:
[first, 1]
[second, 2]
[fourth, 4]
[fifth, 5]
[third, 3]
After lexicographic sort by first column:
[fifth, 5]
[first, 1]
[fourth, 4]
[second, 2]
[third, 3]
After sorting in length order of first column:
[first, 1]
[fifth, 5]
[third, 3]
[second, 2]
[fourth, 4]
After lexicographic sort by second column:
[first, 1]
[second, 2]
[third, 3]
[fourth, 4]
[fifth, 5]
After reverse lexicographic sort by second column:
[fifth, 5]
[fourth, 4]
[third, 3]
[second, 2]
[first, 1]
</pre>
=={{header|XSLT}}==
You can give any template parameter a default value using the optional "select" attribute.
<syntaxhighlight lang="xml"><xsl:template name="sort">
<xsl:param name="table" />
<xsl:param name="ordering" select="'lexicographic'" />
<xsl:param name="column" select="1" />
<xsl:param name="reversed" select="false()" />
...
</xsl:template></syntaxhighlight>
=={{header|Yabasic}}==
<syntaxhighlight lang="yabasic">sub power(n, p)
if numparams = 1 p = 2
return n^p
end sub
print power(2)
print power(2, 3)</syntaxhighlight>
=={{header|zkl}}==
zkl does left to right parameters, each with an optional default. No named parameters (ala Smalltalk). There isn't type enforcement either, a parameter can be anything (although you can set a hint to tell the compiler what you think it will be). If you do want to play named parameters, you can pass in a dictionary (ala Python). The parameters are basically a [varargs] list that you can access in traditional ways.
<syntaxhighlight lang="zkl">const lex="L";
fcn mystrySort(table,ordering=lex,column=0,reverse=False,other){
vm.arglist.println();
}
mystrySort.prototype.println();
mystrySort("table");
mystrySort("table",lex,1);
mystrySort("table",lex,1,True,D("row",35,"type","foobar"));
</syntaxhighlight>
{{out}}
<pre>
L("table","ordering","column","reverse","other")
L("table","L",0,False)
L("table","L",1,False)
L("table","L",1,True,D(type:foobar,row:35))
</pre>
{{omit from|GUISS}}
{{omit from|TI-83 BASIC}} {{omit from|TI-89 BASIC}}
{{omit from|ZX Spectrum Basic|has neither option argument support or inbuilt sorting}}
[[Category: Functions and subroutines]]
[[Category: Sorting]]
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