Reflection/List properties: Difference between revisions
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{{task|Reflection}} [[Category:Programming Tasks]] [[Category:Object oriented]]
{{omit from|C}}
{{omit from|C++}}
{{omit from|Modula-2}}
{{omit from|Rust}}
;Task:
Line 5 ⟶ 9:
Some languages support dynamic properties, which in general can only be inspected if a class' public API includes a way of listing them.
=={{header|C sharp}}==
{{works with|C sharp|7}}
<syntaxhighlight lang="csharp">using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
public static class Reflection
{
public static void Main() {
var t = new TestClass();
var flags = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance;
foreach (var prop in GetPropertyValues(t, flags)) {
Console.WriteLine(prop);
}
foreach (var field in GetFieldValues(t, flags)) {
Console.WriteLine(field);
}
}
public static IEnumerable<(string name, object value)> GetPropertyValues<T>(T obj, BindingFlags flags) =>
from p in typeof(T).GetProperties(flags)
where p.GetIndexParameters().Length == 0 //To filter out indexers
select (p.Name, p.GetValue(obj, null));
public static IEnumerable<(string name, object value)> GetFieldValues<T>(T obj, BindingFlags flags) =>
typeof(T).GetFields(flags).Select(f => (f.Name, f.GetValue(obj)));
class TestClass
{
private int privateField = 7;
public int PublicNumber { get; } = 4;
private int PrivateNumber { get; } = 2;
}
}</syntaxhighlight>
{{out}}
<pre>
(PublicNumber, 4)
(PrivateNumber, 2)
(privateField, 7)
(<PublicNumber>k__BackingField, 4)
(<PrivateNumber>k__BackingField, 2)
</pre>
=={{header|D}}==
<syntaxhighlight lang="d">import std.stdio;
struct S {
bool b;
void foo() {}
private void bar() {}
}
class C {
bool b;
void foo() {}
private void bar() {}
}
void printProperties(T)() if (is(T == class) || is(T == struct)) {
import std.stdio;
import std.traits;
writeln("Properties of ", T.stringof, ':');
foreach (m; __traits(allMembers, T)) {
static if (__traits(compiles, (typeof(__traits(getMember, T, m))))) {
alias typeof(__traits(getMember, T, m)) ti;
static if (!isFunction!ti) {
writeln(" ", m);
}
}
}
}
void main() {
printProperties!S;
printProperties!C;
}</syntaxhighlight>
{{out}}
<pre>Properties of S:
b
Properties of C:
b</pre>
=={{header|Ecstasy}}==
For any object, the type of that object provides access to its properties:
<syntaxhighlight lang="ecstasy">
module test {
void run() {
@Inject Console console;
Property[] properties = &this.actualType.properties;
console.print($"The properties of {this}: {properties}");
}
}
</syntaxhighlight>
{{out}}
<pre>
x$ xec test
The properties of test: [immutable Array<Class<Object, Object, Object, Struct>> classes, immutable Map<String, Class<Object, Object, Object, Struct>> classByName, String simpleName, String qualifiedName, Version version, immutable Map<String, Module> modulesByPath]
</pre>
=={{header|Elena}}==
ELENA 6.x :
<syntaxhighlight lang="elena">import system'routines;
import system'dynamic;
import extensions;
class MyClass
{
int X : prop;
string Y : prop;
}
public program()
{
var o := new MyClass
{
this X := 2;
this Y := "String";
};
MyClass.__getProperties().forEach::(p)
{
console.printLine("o.",p,"=",p.getPropertyValue(o))
}
}</syntaxhighlight>
{{out}}
<pre>
o.X=2
o.Y=String
</pre>
=={{header|Factor}}==
Mirrors present an object's slots and slot values as an associative structure.
<syntaxhighlight lang="factor">USING: assocs kernel math mirrors prettyprint strings ;
TUPLE: foo
{ bar string }
{ baz string initial: "hi" }
{ baxx integer initial: 50 read-only } ;
C: <foo> foo
"apple" "banana" 200 <foo> <mirror>
[ >alist ] [ object-slots ] bi [ . ] bi@</syntaxhighlight>
{{out}}
<pre>
{ { "bar" "apple" } { "baz" "banana" } { "baxx" 200 } }
{
T{ slot-spec
{ name "bar" }
{ offset 2 }
{ class string }
{ initial "" }
}
T{ slot-spec
{ name "baz" }
{ offset 3 }
{ class string }
{ initial "hi" }
}
T{ slot-spec
{ name "baxx" }
{ offset 4 }
{ class integer }
{ initial 50 }
{ read-only t }
}
}
</pre>
=={{header|Fortran}}==
Line 12 ⟶ 192:
There may be a list of items, not just the lone <code>X</code> and these proceedings apply to READ statements also.
=={{header|Go}}==
<syntaxhighlight lang="go">package main
import (
"fmt"
"image"
"reflect"
)
// A type definition
type t struct {
X int
next *t
}
func main() {
report(t{})
report(image.Point{})
}
func report(x interface{}) {
t := reflect.TypeOf(x)
n := t.NumField()
fmt.Printf("Type %v has %d fields:\n", t, n)
fmt.Println("Name Type Exported")
for i := 0; i < n; i++ {
f := t.Field(i)
fmt.Printf("%-8s %-8v %-8t\n",
f.Name,
f.Type,
f.PkgPath == "",
)
}
fmt.Println()
}</syntaxhighlight>
{{out}}
<pre>
Type main.t has 2 fields:
Name Type Exported
X int true
next *main.t false
Type image.Point has 2 fields:
Name Type Exported
X int true
Y int true
</pre>
=={{header|Groovy}}==
{{trans|Java}}
<syntaxhighlight lang="groovy">import java.lang.reflect.Field
@SuppressWarnings("unused")
class ListProperties {
public int examplePublicField = 42
private boolean examplePrivateField = true
static void main(String[] args) {
ListProperties obj = new ListProperties()
Class clazz = obj.class
println "All public fields (including inherited):"
(clazz.fields).each { Field f ->
printf "%s\t%s\n", f, f.get(obj)
}
println()
println "All declared fields (excluding inherited):"
clazz.getDeclaredFields().each { Field f ->
f.accessible = true
printf "%s\t%s\n", f, f.get(obj)
}
}
}</syntaxhighlight>
{{out}}
<pre>All public fields (including inherited):
public int ListProperties.examplePublicField 42
public static transient boolean ListProperties.__$stMC false
All declared fields (excluding inherited):
public int ListProperties.examplePublicField 42
private boolean ListProperties.examplePrivateField true
private static org.codehaus.groovy.reflection.ClassInfo ListProperties.$staticClassInfo org.codehaus.groovy.reflection.ClassInfo@400cff1a
public static transient boolean ListProperties.__$stMC false
private transient groovy.lang.MetaClass ListProperties.metaClass groovy.lang.MetaClassImpl@275710fc[class ListProperties]
private static org.codehaus.groovy.reflection.ClassInfo ListProperties.$staticClassInfo$ null
private static java.lang.ref.SoftReference ListProperties.$callSiteArray java.lang.ref.SoftReference@525f1e4e</pre>
=={{header|J}}==
http://rosettacode.org/wiki/Reflection/List_methods#J
Please observe that names&>i.4 lists nouns (pronouns that store data), adverbs (names of verb modifiers returning any of these four parts of speech), conjunctions (which can take three or four arguments, two of which can any part of these four parts of speech and two nouns), and proverbs (names of verbs, which you might call "functions").
=={{header|Java}}==
<
public class ListFields {
Line 34 ⟶ 306:
}
}
}</
{{out}}
<pre>
Line 48 ⟶ 320:
There are multiple ways of getting property names, each of which include different subsets of an object's properties, such as enumerable or inherited properties. Properties in JavaScript can be enumerable or non-enumerable; enumerable properties are accessable when looping over the object with <code>for</code>. <code>Object.getOwnPropertyNames()</code>.
<
name: 'proto',
proto: true,
Line 79 ⟶ 351:
Object.entries(obj);
//[["name", "obj"], ["obj", true], ["doStuff", function()]]
</syntaxhighlight>
=={{header|jq}}==
{{works with|jq}}
Various properties of JSON values are directly accessible via the
built-in functions `type`, `length` (except for booleans), and, for
JSON objects, `keys` and `keys_unsorted`:
* `type` returns the JSON type;
* `length` returns an array's length, the number of (distinct) keys of an object, the absolute value of a number, and 0 for `null`;
Note that gojq (the Go implementation of jq) does not support `keys_unsorted`.
Other properties can be ascertained programmatically.
See e.g. '''schema.jq''' (https://gist.github.com/pkoppstein/a5abb4ebef3b0f72a6ed) for a schema-inference engine for JSON written in jq; the inferred schemas are themselves JSON documents.
'''Example'''
<syntaxhighlight lang="jq">
# Use jq's built-ins to generate a (recursive) synopsis of .
def synopsis:
if type == "boolean" then "Type: \(type)"
elif type == "object"
then "Type: \(type) length:\(length)",
(keys_unsorted[] as $k
| "\($k): \(.[$k] | synopsis )")
else "Type: \(type) length: \(length)"
end;
true, null, [1,2], {"a": {"b": 3, "c": 4}, "x": "Rosetta Code"}, now
| ("\n\(.) ::", synopsis)
</syntaxhighlight>
{{out}}
<pre>
true ::
Type: boolean
null ::
Type: null length: 0
[1,2] ::
Type: array length: 2
{"a":{"b":3,"c":4},"x":[0,1]} ::
Type: object length:2
a: Type: object length:2
a: b: Type: number length: 3
a: c: Type: number length: 4
x: Type: string length: 12
1629526284.540229 ::
Type: number length: 1629526284.540229
</pre>
=={{header|Julia}}==
{{works with|Julia|0.6}}
<
println("\nObject: $obj\nDescription:")
dump(obj)
end</
{{out}}
Line 117 ⟶ 442:
=={{header|Kotlin}}==
<
import kotlin.reflect.full.memberProperties
Line 142 ⟶ 467:
println("${prop.name.padEnd(13)} -> ${prop.get(example)}")
}
}</
{{out}}
Line 156 ⟶ 481:
=={{header|Lingo}}==
<
obj.foo = 23
obj.bar = 42
Line 166 ⟶ 491:
repeat with i = 1 to cnt
put obj.getPropAt(i)&" = "&obj[i]
end repeat</
{{Out}}
Line 173 ⟶ 498:
-- "foo = 23"
</pre>
=={{header|Lua}}==
<syntaxhighlight lang="lua">a = 1
b = 2.0
c = "hello world"
function listProperties(t)
if type(t) == "table" then
for k,v in pairs(t) do
if type(v) ~= "function" then
print(string.format("%7s: %s", type(v), k))
end
end
end
end
print("Global properties")
listProperties(_G)
print("Package properties")
listProperties(package)</syntaxhighlight>
{{out}}
<pre>Global properties
number: a
table: string
number: b
table: package
table: os
table: io
table: arg
string: c
table: math
table: debug
table: table
table: coroutine
table: _G
string: _VERSION
Package properties
table: preload
table: loaded
table: loaders
string: cpath
string: config
string: path</pre>
=={{header|Nanoquery}}==
<syntaxhighlight lang="nanoquery">// declare a class that has fields to be listed
class Fields
declare static field1 = "this is a static field. it will not be listed"
declare field2
declare field3
declare field4
end
// list all the fields in the class
for fieldname in Fields.getFieldNames()
println fieldname
end</syntaxhighlight>
{{out}}
<pre>field3
field2
field4</pre>
=={{header|Nim}}==
<syntaxhighlight lang="nim">type
Foo = object
a: float
b: string
c: seq[int]
let f = Foo(a: 0.9, b: "hi", c: @[1,2,3])
for n, v in f.fieldPairs:
echo n, ": ", v</syntaxhighlight>
{{out}}
<pre>a: 0.9
b: hi
c: @[1, 2, 3]</pre>
=={{header|Objective-C}}==
<
#import <objc/runtime.h>
Line 230 ⟶ 630:
return 0;
}</
{{out}}
<pre>
Line 241 ⟶ 641:
</pre>
=={{header|
Whereas in PL/I variables habe a (declared) type, in REXX and ooRexx a "typeless" variable
can be assigned a string or object, respectively.
The datatype builtin function can be used to determine the data type of a given string.
Many of these options are also supported by other REXX implementations.
<syntaxhighlight lang="oorexx">/* REXX demonstrate uses of datatype() */
/* test values */
d.1=''
d.2='a23'
d.3='101'
d.4='123'
d.5='12345678901234567890'
d.6='abc'
d.7='aBc'
d.8='1'
d.9='0'
d.10='Walter'
d.11='ABC'
d.12='f23'
d.13='123'
/* supported options */
t.1='A' /* Alphanumeric */
t.2='B' /* Binary */
t.3='I' /* Internal whole number */
t.4='L' /* Lowercase */
t.5='M' /* Mixed case */
t.6='N' /* Number */
t.7='O' /* lOgical */
t.8='S' /* Symbol */
t.9='U' /* Uppercase */
t.10='V' /* Variable */
t.11='W' /* Whole number */
t.12='X' /* heXadecimal */
t.13='9' /* 9 digits */
hdr=left('',20)
Do j=1 To 13
hdr=hdr t.j
End
hdr=hdr 'datatype(v)'
Say hdr
Do i=1 To 13
ol=left(d.i,20)
Do j=1 To 13
ol=ol datatype(d.i,t.j)
End
ol=ol datatype(d.i)
Say ol
End
Say hdr</syntaxhighlight>
{{out}}
<pre> A B I L M N O S U V W X 9 datatype(v)
0 1 0 0 0 0 0 0 0 0 0 1 0 CHAR
a23 1 0 0 0 0 0 0 1 0 1 0 1 0 CHAR
101 1 1 1 0 0 1 0 1 0 0 1 1 1 NUM
123 1 0 1 0 0 1 0 1 0 0 1 1 1 NUM
12345678901234567890 1 0 0 0 0 1 0 1 0 0 0 1 0 NUM
abc 1 0 0 1 1 0 0 1 0 1 0 1 0 CHAR
aBc 1 0 0 0 1 0 0 1 0 1 0 1 0 CHAR
1 1 1 1 0 0 1 1 1 0 0 1 1 1 NUM
0 1 1 1 0 0 1 1 1 0 0 1 1 1 NUM
Walter 1 0 0 0 1 0 0 1 0 1 0 0 0 CHAR
ABC 1 0 0 0 1 0 0 1 1 1 0 1 0 CHAR
f23 1 0 0 0 0 0 0 1 0 1 0 1 0 CHAR
123 1 0 1 0 0 1 0 1 0 0 1 1 1 NUM
A B I L M N O S U V W X 9 datatype(v)</pre>
=={{header|Perl}}==
In Perl's bare-bones native OO system, an object is sometimes nothing more than a hash blessed into a class. It's properties could be simply listed by iterating over the keys. However more complex data structures can be present, so the safest option is always to use <code>Data::Dumper</code> to examine an object.
<syntaxhighlight lang="perl">{
package Point;
use Class::Spiffy -base;
field 'x';
field 'y';
}
{
package Circle;
use base qw(Point);
field 'r';
}
my $p1 = Point->new(x => 8, y => -5);
my $c1 = Circle->new(r => 4);
my $c2 = Circle->new(x => 1, y => 2, r => 3);
use Data::Dumper;
say Dumper $p1;
say Dumper $c1;
say Dumper $c2;</syntaxhighlight>
{{out}}
<pre>$VAR1 = bless( {
'x' => 8,
'y' => -5
}, 'Point' );
$VAR1 = bless( {
'r' => 4
}, 'Circle' );
$VAR1 = bless( {
'r' => 3,
'x' => 1,
'y' => 2
}, 'Circle' );
</pre>
=={{header|Phix}}==
{{libheader|Phix/Class}}
Needs 0.8.1+
Note that content from and parameters to get_struct_type/fields() may change between releases.<br>
You should certainly be prepared for them to return NULL for unrecognised field names and types.<br>
Technically the code below is re-fetching tid and flags before returning them in a textual format.
<!--<syntaxhighlight lang="phix">-->
<span style="color: #008080;">class</span> <span style="color: #000000;">c</span> <span style="color: #7060A8;">nullable</span>
<span style="color: #004080;">integer</span> <span style="color: #004080;">int</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">1</span>
<span style="color: #008080;">public</span> <span style="color: #004080;">atom</span> <span style="color: #000000;">atm</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">2.3</span>
<span style="color: #004080;">string</span> <span style="color: #000000;">str</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">"4point5"</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">seq</span>
<span style="color: #008080;">public</span><span style="color: #0000FF;">:</span>
<span style="color: #004080;">object</span> <span style="color: #000000;">obj</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{</span><span style="color: #008000;">"an object"</span><span style="color: #0000FF;">}</span>
<span style="color: #000000;">c</span> <span style="color: #000000;">child</span>
<span style="color: #008080;">private</span> <span style="color: #008080;">function</span> <span style="color: #000000;">foo</span><span style="color: #0000FF;">();</span>
<span style="color: #008080;">public</span> <span style="color: #008080;">procedure</span> <span style="color: #000000;">bar</span><span style="color: #0000FF;">();</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">class</span>
<span style="color: #000000;">c</span> <span style="color: #000000;">c_instance</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">new</span><span style="color: #0000FF;">()</span>
<span style="color: #008080;">include</span> <span style="color: #000000;">builtins</span><span style="color: #0000FF;">\</span><span style="color: #000000;">structs</span><span style="color: #0000FF;">.</span><span style="color: #000000;">e</span> <span style="color: #7060A8;">as</span> <span style="color: #000000;">structs</span>
<span style="color: #008080;">function</span> <span style="color: #000000;">nulls</span><span style="color: #0000FF;">(</span><span style="color: #004080;">object</span> <span style="color: #000000;">s</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">return</span> <span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">s</span><span style="color: #0000FF;">=</span><span style="color: #004600;">NULL</span><span style="color: #0000FF;">?</span><span style="color: #008000;">"NULL"</span><span style="color: #0000FF;">:</span><span style="color: #000000;">s</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;">fields</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">structs</span><span style="color: #0000FF;">:</span><span style="color: #000000;">get_struct_fields</span><span style="color: #0000FF;">(</span><span style="color: #000000;">c</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">fields</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span>
<span style="color: #0000FF;">{</span><span style="color: #004080;">string</span> <span style="color: #000000;">name</span><span style="color: #0000FF;">,</span> <span style="color: #004080;">integer</span> <span style="color: #000000;">tid</span><span style="color: #0000FF;">,</span> <span style="color: #004080;">integer</span> <span style="color: #000000;">flags</span><span style="color: #0000FF;">}</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">fields</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span>
<span style="color: #008080;">if</span> <span style="color: #008080;">not</span> <span style="color: #7060A8;">and_bits</span><span style="color: #0000FF;">(</span><span style="color: #000000;">flags</span><span style="color: #0000FF;">,</span><span style="color: #000000;">SF_RTN</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">then</span> <span style="color: #000080;font-style:italic;">-- (exclude foo/bar)</span>
<span style="color: #004080;">string</span> <span style="color: #000000;">t</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">nulls</span><span style="color: #0000FF;">(</span><span style="color: #000000;">structs</span><span style="color: #0000FF;">:</span><span style="color: #000000;">get_field_type</span><span style="color: #0000FF;">(</span><span style="color: #000000;">c</span><span style="color: #0000FF;">,</span><span style="color: #000000;">name</span><span style="color: #0000FF;">,</span><span style="color: #004600;">true</span><span style="color: #0000FF;">)),</span>
<span style="color: #000000;">f</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">nulls</span><span style="color: #0000FF;">(</span><span style="color: #000000;">structs</span><span style="color: #0000FF;">:</span><span style="color: #000000;">get_field_flags</span><span style="color: #0000FF;">(</span><span style="color: #000000;">c</span><span style="color: #0000FF;">,</span><span style="color: #000000;">name</span><span style="color: #0000FF;">,</span><span style="color: #004600;">true</span><span style="color: #0000FF;">))</span>
<span style="color: #004080;">object</span> <span style="color: #000000;">v</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">nulls</span><span style="color: #0000FF;">(</span><span style="color: #000000;">structs</span><span style="color: #0000FF;">:</span><span style="color: #000000;">fetch_field</span><span style="color: #0000FF;">(</span><span style="color: #000000;">c_instance</span><span style="color: #0000FF;">,</span><span style="color: #000000;">name</span><span style="color: #0000FF;">,</span><span style="color: #000000;">c</span><span style="color: #0000FF;">))</span>
<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;">"type:%-11s, name:%-5s, flags:%s, value:%v\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">t</span><span style="color: #0000FF;">,</span><span style="color: #000000;">name</span><span style="color: #0000FF;">,</span><span style="color: #000000;">f</span><span style="color: #0000FF;">,</span><span style="color: #000000;">v</span><span style="color: #0000FF;">})</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<!--</syntaxhighlight>-->
{{out}}
<pre>
type:ST_INTEGER , name:int , flags:SF_PRIVATE, value:1
type:ST_ATOM , name:atm , flags:SF_PUBLIC, value:2.3
type:ST_STRING , name:str , flags:SF_PRIVATE, value:"4point5"
type:ST_SEQUENCE, name:seq , flags:SF_PRIVATE, value:{}
type:ST_OBJECT , name:obj , flags:SF_PUBLIC, value:{"an object"}
type:c , name:child, flags:SF_PUBLIC, value:"NULL"
</pre>
=={{header|PHP}}==
<
class Foo {
}
Line 276 ⟶ 806:
var_dump(get_object_vars($obj));
?></
{{out}}
<pre>
Line 286 ⟶ 816:
}
</pre>
=={{header|PicoLisp}}==
The function <code>show</code> can be used to print all properties of an object.
First we define a rectangle class <code>+Rectangle</code> as subclass of a shape class <code>+Shape</code>:
<syntaxhighlight lang="picolisp">
# The Rectangle class
(class +Rectangle +Shape)
# dx dy
(dm T (X Y DX DY)
(super X Y)
(=: dx DX)
(=: dy DY) )
(dm area> ()
(* (: dx) (: dy)) )
(dm perimeter> ()
(* 2 (+ (: dx) (: dy))) )
(dm draw> ()
(drawRect (: x) (: y) (: dx) (: dy)) ) # Hypothetical function 'drawRect'
</syntaxhighlight>
Then we can create an object of the +Rectangle class and check its properties using the <code>show</code> function.
<syntaxhighlight lang="text">
: (setq R (new '(+Rectangle) 0 0 30 20))
-> $177356065126400
: (show R)
$177715702441044 (+Rectangle)
dy 20
dx 30
y 0
x 0
-> $177715702441044
</syntaxhighlight>
=={{header|PL/I}}==
Line 294 ⟶ 865:
Here we find the properties of a <code>[DateTime]</code> object:
<syntaxhighlight lang="powershell">
Get-Date | Get-Member -MemberType Property
</syntaxhighlight>
{{Out}}
Line 319 ⟶ 890:
</pre>
The "Add" methods of a <code>[DateTime]</code> object:
<syntaxhighlight lang="powershell">
Get-Date | Get-Member -MemberType Method -Name Add*
</syntaxhighlight>
{{Out}}
<pre>
Line 342 ⟶ 913:
The <code>[https://docs.python.org/3.5/library/functions.html#dir dir()]</code> function and Python's <code>[https://docs.python.org/3.5/library/inspect.html#module-inspect inspect]</code> module both will list properties.
<
__priv = 'private'
Line 423 ⟶ 994:
inspect.getmembers(chld)
#[('__class__', <class '__main__.Child'>), ..., ('args', (0, 'I', 'two')), ('args_bleh', "(0, 'I', 'two') bleh"), ('doNothing', <bound method Child.doNothing of Child(chld, 0, 'I', 'two')>), ('doStuff', <bound method Child.doStuff of Child(chld, 0, 'I', 'two')>), ('name', 'chld'), ('name_bleh', 'chld bleh'), ('own', "chld's own"), ('own_bleh', "chld's own bleh"), ('reBleh', <_sre.SRE_Pattern object at 0x10067bd20>), ('reBleh_bleh', '<_sre.SRE_Pattern object at 0x10067bd20> bleh')]
</syntaxhighlight>
=={{header|Raku}}==
(formerly Perl 6)
You can get a list of an object's attributes (instance variables) using <tt>.^attributes</tt>, which is part of the [https://docs.raku.org/type/Metamodel$COLON$COLONClassHOW Meta Object Protocol]..<br>
Each is represented as an <tt>Attribute</tt> object that contains a bunch of info:
<syntaxhighlight lang="raku" line>class Foo {
has $!a = now;
has Str $.b;
has Int $.c is rw;
}
my $object = Foo.new: b => "Hello", c => 42;
for $object.^attributes {
say join ", ", .name, .readonly, .container.^name, .get_value($object);
}</syntaxhighlight>
{{out}}
<pre>
$!a, True, Any, Instant:1470517602.295992
$!b, True, Str, Hello
$!c, False, Int, 42
</pre>
Public attributes (in this case, <tt>$.b</tt> and <tt>$.c</tt>) are really just attributes for which the compiler also auto-generates a method of the same name. See [[Reflection/List_methods#Raku]].
=={{header|REXX}}==
===version 1===
(This REXX version is modeled after the '''PL/I''' entry.)
The '''say''' instruction can display a value (
the console (terminal) as well as
Since ''everything'' in REXX is a character string, the ''type'' of the
Line 438 ⟶ 1,037:
A simplistic example:
<
abc.j= -4.12
say 'variable abc.2 (length' length(abc.2)')=' abc.2</
<br><br>
===version 2===
<syntaxhighlight lang="rexx">/* REXX shows the "equivalent" to PL/I's PUT DATA for a simple variable */
/* put_data2('a.') to show all a.tail values isn't that easy :-) */
j=2
abc.j= -4.12
Say put_data('abc.2') /* Put Data(abc(2)) */
string=put_data('abc.2') /* Put string(string) Data(abc(2)) */
Say string
Exit
put_data:
Parse Arg variable
return(variable'='''value(variable)'''')</syntaxhighlight>
{{out}}
<pre>abc.2='-4.12'
abc.2='-4.12'</pre>
=={{header|Ruby}}==
<
@@xyz = nil
def initialize(name, age)
Line 474 ⟶ 1,088:
p Foo.class_variable_get(:@@xyz) #=> :xyz
p Foo.class_variable_set(:@@abc, 123) #=> 123
p Foo.class_variables #=> [:@@xyz, :@@abc]</
=={{header|Scala}}==
===Java Interoperability===
{{Out}}Best seen running in your browser [https://scastie.scala-lang.org/MdkPxH6yTlS4W8TaXYxSgA Scastie (remote JVM)].
<syntaxhighlight lang="scala">object ListProperties extends App {
private val obj = new {
val examplePublicField: Int = 42
private val examplePrivateField: Boolean = true
}
private val clazz = obj.getClass
println("All public methods (including inherited):")
clazz.getFields.foreach(f => println(s"${f}\t${f.get(obj)}"))
println("\nAll declared fields (excluding inherited):")
clazz.getDeclaredFields.foreach(f => println(s"${f}}"))
}</syntaxhighlight>
=={{header|Smalltalk}}==
for names of slots defined in the class (excludes inherited):
<syntaxhighlight lang="smalltalk">someObject class instVarNames</syntaxhighlight>
for all slot names (incl. inherited):
<syntaxhighlight lang="text">someObject class allInstVarNames</syntaxhighlight>
to get a Dictionary (aka. HashTable) mapping names to values:
<syntaxhighlight lang="text">someObject class allInstVarNames collect:[:nm | nm -> (someObject instVarNamed:nm)] as:Dictionary</syntaxhighlight>
A class can make this a secret by redefining #instVar access to eg. raise an exception.
Notice: this is not considered good Smalltalk style - it should be used by debuggers and object inspectors only, except for special frameworks (such as code generators etc.).
=={{header|Tcl}}==
Line 480 ⟶ 1,122:
For objects supporting this protocol, you can list all options by invoking the <tt>configure</tt> method without arguments (result split over multiple lines for readability):
<syntaxhighlight lang="tcl">% package require Tk
8.6.5
% . configure
Line 491 ⟶ 1,132:
{-highlightcolor highlightColor HighlightColor #000000 #000000}
{-highlightthickness highlightThickness HighlightThickness 0 0} {-padx padX Pad 0 0} {-pady padY Pad 0 0}
{-takefocus takeFocus TakeFocus 0 0} {-visual visual Visual {} {}} {-width width Width 0 0}</
Two-element sublists (eg <tt>-bd -borderwidth</tt>) represent aliases, and five-element sublists are of the form <tt>{optionName dbName dbClass defaultValue currentValue}</tt>. <tt>dbName</tt> and <tt>dbClass</tt> are related to how the option is specified in the <i>option database</i>.
Line 497 ⟶ 1,138:
Simply listing the option names is like this:
<
-borderwidth -class -menu -relief -screen -use -background -colormap -container -cursor -height
-highlightbackground -highlightcolor -highlightthickness -padx -pady -takefocus -visual -width</syntaxhighlight>
=={{header|Visual Basic .NET}}==
{{trans|C#}}
<syntaxhighlight lang="vbnet">Imports System.Reflection
Module Module1
Class TestClass
Private privateField = 7
Public ReadOnly Property PublicNumber = 4
Private ReadOnly Property PrivateNumber = 2
End Class
Function GetPropertyValues(Of T)(obj As T, flags As BindingFlags) As IEnumerable
Return From p In obj.GetType().GetProperties(flags)
Where p.GetIndexParameters().Length = 0
Select New With {p.Name, Key .Value = p.GetValue(obj, Nothing)}
End Function
Function GetFieldValues(Of T)(obj As T, flags As BindingFlags) As IEnumerable
Return obj.GetType().GetFields(flags).Select(Function(f) New With {f.Name, Key .Value = f.GetValue(obj)})
End Function
Sub Main()
Dim t As New TestClass()
Dim flags = BindingFlags.Public Or BindingFlags.NonPublic Or BindingFlags.Instance
For Each prop In GetPropertyValues(t, flags)
Console.WriteLine(prop)
Next
For Each field In GetFieldValues(t, flags)
Console.WriteLine(field)
Next
End Sub
End Module</syntaxhighlight>
{{out}}
<pre>{ Name = PublicNumber, Value = 4 }
{ Name = PrivateNumber, Value = 2 }
{ Name = privateField, Value = 7 }
{ Name = _PublicNumber, Value = 4 }
{ Name = _PrivateNumber, Value = 2 }</pre>
=={{header|Wren}}==
Wren doesn't currently have reflection as such but it's possible to identify a class's properties and list them at runtime by placing a suitable attribute on the class.
Note that, since attributes are stored internally as a map, the order in which the property names appear is undefined.
<syntaxhighlight lang="wren">#! instance_methods(m, n, o)
#! instance_properties(p, q, r)
class C {
construct new() {}
m() {}
n() {}
o() {}
p {}
q {}
r {}
}
var c = C.new() // create an object of type C
System.print("List of properties available for object 'c':")
for (property in c.type.attributes.self["instance_properties"]) System.print(property.key)</syntaxhighlight>
{{out}}
<pre>
List of properties available for object 'c':
r
q
p
</pre>
=={{header|zkl}}==
Line 506 ⟶ 1,221:
Every object has a "properties" method, which returns a list of property names [for that object].
<
properties.println();
List(1,2,3).property(properties[0]).println(); // get value
List(1,2,3).Property(properties[0])().println(); // method that gets value
List(1,2,3).BaseClass(properties[0]).println(); // another way to get value</
{{out}}
<pre>
| |||