Stack traces: Difference between revisions
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Many programming languages allow for introspection of the current call stack environment. This can be for a variety of purposes such as enforcing security checks, debugging, or for getting access to the stack frame of callers.
;Task:
Print out (in a manner considered suitable for the platform) the current call stack.
The amount of information printed for each frame on the call stack is not constrained, but should include at least the name of the function or method at that level of the stack frame.
You may explicitly add a call to produce the stack trace to the (example) code being instrumented for examination.
The task should allow the program to continue after generating the stack trace.
The task report here must include the trace from a sample program.
<br><br>
=={{header|Ada}}==
{{works with|GNAT}}
The provided solution is specific to the [[GNAT]] Ada compiler. Further it is restricted to some platforms. See the description of the package GNAT.Traceback supplied with [[GNAT]]. The switch -g must be used in order to include debug information into the executable.
<syntaxhighlight lang
with
with
procedure Test_Stack_Trace is
procedure Call_Stack is
Trace : GNAT.Traceback.Tracebacks_Array (1..1_000);
Length : Natural;
begin
GNAT.Traceback.Call_Chain (Trace, Length);
Put_Line (GNAT.Traceback.Symbolic.Symbolic_Traceback (Trace (1..Length)));
end Call_Stack;
Line 40 ⟶ 49:
begin
Outer (2,3,5);
end Test_Stack_Trace;</
Sample output:
<pre>
Line 54 ⟶ 63:
7C817075 in ?? at ??:0
</pre>
=={{header|AutoHotkey}}==
The local, static, and global bindings are viewable using 'Listvars'
<br> recently executed lines are available through ListLines
Line 61 ⟶ 70:
ListLines can be turned on or off... with:
<br> ListLines, On|Off
<
return
Line 77 ⟶ 86:
msgbox, variable bindings
}
#Persistent</
Output:
<syntaxhighlight lang="autohotkey">001: f()
006: Return,g()
011: ListLines (0.05)
012: MsgBox,lines recently executed (3.81)
013: x = local to g
014: ListVars
015: MsgBox,variable bindings (3.94)
016: }
002: Return (181.66)
Global Variables (alphabetical)
--------------------------------------------------
0[1 of 3]: 0
ErrorLevel[1 of 3]: 0
</syntaxhighlight>
=={{header|BASIC}}==
Line 149 ⟶ 174:
=={{header|C}}==
=== Using GNU extensions ===
{{works with|POSIX}}
Line 157 ⟶ 183:
In order to be able to see the symbols, we need to link with an option telling to export symbols names in the dynamic section (for ELF and targets supporting it); for gcc, it means using the option <tt>-rdynamic</tt> (or <tt>-export-dynamic</tt> in the GNU linker). Otherwise we see only addresses. Static functions will always have their names "hidden".
<
#include <stdlib.h>
#include <unistd.h>
Line 195 ⟶ 221:
outer(2,3,5);
return EXIT_SUCCESS;
}</
Sample output on my system:
Line 207 ⟶ 233:
/lib/i686/libc.so.6(__libc_start_main+0xe5)[0xb7e045c5]
./pst[0x80485d1]</pre>
=== Using no extensions ===
Sometimes microcomputers do not come with any kind of debug or stack tracing routines. Typically a program would "just hang" somewhere, or crash the gadget. This then requires manually "wolf fencing" of the bug with ''printf'' statements to identify the C source file, then the procedure, and then the line at the point of system crash.
The following macros and procedures provide an alternative way of doing this trouble shooting.
The steps are:
* #include "stack_trace.h" in the suspect C source code.
* Change the initial and last { and } of each procedure in the code to BEGIN(proc_name) and END.
* #define STACK_TRACE_ON and assign stack_trace.on to TRUE
* Recompile and run....
The resulting output can be used to locate offending procedure and - hopefully - give a hint to the location of the actual bug.
The key point is that the following can be done on systems that are equipped with only and editor and compiler, and no debugger or library extension.
'''==> stack_trace.h <=='''
<syntaxhighlight lang="c">
/* stack_trace.c - macros for hinting/tracing where a program crashed
on a system _without_ any form of debugger.
Simple goodbye_cruel_world.c example:
#include <stdio.h>
#include <stdlib.h>
#define STACK_TRACE_ON // compile in these "stack_trace" routines
#include "stack_trace.h"
void goodbye_cruel_world()
BEGIN(goodbye_cruel_world)
print_stack_trace();
for(;;){}
END
int main()
BEGIN(main)
stack_trace.on = TRUE; // turn on runtime tracing
goodbye_cruel_world();
stack_trace.on = FALSE;
RETURN(EXIT_SUCCESS);
END
Output:
goodbye_cruel_world.c:8: BEGIN goodbye_cruel_world[0x80486a8], stack(depth:1, size:60)
goodbye_cruel_world.c:8: goodbye_cruel_world[0x80486a8] --- stack(depth:2, size:60) ---
goodbye_cruel_world.c:14: main[0x80486f4] --- stack(depth:1, size:0) ---
goodbye_cruel_world.c:8: --- (depth 2) ---
*/
#ifndef _LINUX_STDDEF_H
#include <stddef.h>
#endif
typedef struct stack_trace_frame_s {
const char *file_name;
int file_line;
const char *proc_name;
void *proc_addr;
struct stack_trace_frame_s *down, *up;
} stack_trace_frame_t;
#define SKIP
typedef enum {TRUE=1, FALSE=0} bool_t;
typedef struct {
bool_t on;
struct { const char *_begin, *_print, *_return, *_exit, *_end; } fmt;
struct { int depth; stack_trace_frame_t *lwb, *upb; } stack;
struct { int lwb, by, upb; const char *prefix; } indent;
} stack_trace_t;
extern stack_trace_t stack_trace;
void stack_trace_begin(char *SKIP, stack_trace_frame_t *SKIP);
void stack_trace_end(char *SKIP, int SKIP);
void print_stack_trace();
#ifdef STACK_TRACE_ON
/* Many ThanX to Steve R Bourne for inspiring the following macros ;-) */
#define BEGIN(x) { auto stack_trace_frame_t this = {__FILE__, __LINE__, #x, &x, NULL, NULL}; \
stack_trace_begin(stack_trace.fmt._begin, &this); {
#define RETURN(x) { stack_trace_end(stack_trace.fmt._return, __LINE__); return(x); }
#define EXIT(x) { stack_trace_end(stack_trace.fmt._exit, __LINE__); exit(x); }
#define END } stack_trace_end(stack_trace.fmt._end, __LINE__); }
#else
/* Apologies to Landon Curt Noll and Larry Bassel for the following macros :-) */
#define BEGIN(x) {
#define RETURN(x) return(x)
#define EXIT(x) exit(x)
#define END }
#endif</syntaxhighlight>
'''==> stack_trace.c <=='''
<syntaxhighlight lang="c">#include <stdio.h>
#include <stddef.h>
#define STACK_TRACE_ON
#include "stack_trace.h"
#define indent_fmt "%s"
#define std_cc_diag_fmt "%s:%d: "
#define stack_trace_diag_fmt " %s[0x%x], stack(depth:%d, size:%u)\n"
#define stack_trace_fmt "%s:%d:\t%s[0x%x]\t--- stack(depth:%d, size:%u) ---\n"
stack_trace_t stack_trace = {
FALSE, /* default: stack_trace.on == FALSE */
{ std_cc_diag_fmt""indent_fmt"BEGIN"stack_trace_diag_fmt,
stack_trace_fmt,
std_cc_diag_fmt""indent_fmt"RETURN"stack_trace_diag_fmt,
std_cc_diag_fmt""indent_fmt"EXIT"stack_trace_diag_fmt,
std_cc_diag_fmt""indent_fmt"END"stack_trace_diag_fmt },
{ 0, (stack_trace_frame_t*)NULL, (stack_trace_frame_t*)NULL }, /* stack */
{ 19, 2, 20, " " } /* indent wrap */
};
void stack_trace_begin(const char *fmt, stack_trace_frame_t *this){
if(stack_trace.on){
fprintf(stderr, fmt,
this->file_name, this->file_line, /* file details */
stack_trace.indent.prefix+stack_trace.indent.lwb,
this->proc_name, this->proc_addr, /* procedure details */
stack_trace.stack.depth, (unsigned)stack_trace.stack.lwb-(unsigned)this);
stack_trace.indent.lwb =
( stack_trace.indent.lwb - stack_trace.indent.by ) % stack_trace.indent.upb;
}
if(!stack_trace.stack.upb){ /* this IS the stack !! */
stack_trace.stack.lwb = stack_trace.stack.upb = this;
} else {
this -> down = stack_trace.stack.upb;
stack_trace.stack.upb -> up = this;
stack_trace.stack.upb = this;
}
stack_trace.stack.depth++;
}
void stack_trace_end(const char *fmt, int line){
stack_trace.stack.depth--;
if(stack_trace.on){
stack_trace.indent.lwb =
( stack_trace.indent.lwb + stack_trace.indent.by ) % stack_trace.indent.upb;
stack_trace_frame_t *this = stack_trace.stack.upb;
fprintf(stderr, fmt,
this->file_name, this->file_line, /* file details */
stack_trace.indent.prefix+stack_trace.indent.lwb,
this->proc_name, this->proc_addr, /* procedure details */
stack_trace.stack.depth, (unsigned)stack_trace.stack.lwb-(unsigned)this);
}
stack_trace.stack.upb = stack_trace.stack.upb -> down;
}
void print_indent(){
if(!stack_trace.stack.upb){
/* fprintf(stderr, "STACK_TRACE_ON not #defined during compilation\n"); */
} else {
stack_trace_frame_t *this = stack_trace.stack.upb;
fprintf(stderr, std_cc_diag_fmt""indent_fmt,
this->file_name, this->file_line, /* file details */
stack_trace.indent.prefix+stack_trace.indent.lwb
);
}
}
void print_stack_trace() {
if(!stack_trace.stack.upb){
/* fprintf(stderr, "STACK_TRACE_ON not #defined during compilation\n"); */
} else {
int depth = stack_trace.stack.depth;
stack_trace_frame_t *this = stack_trace.stack.upb;
for(this = stack_trace.stack.upb; this; this = this->down, depth--){
fprintf(stderr, stack_trace.fmt._print,
this->file_name, this->file_line, /* file details */
this->proc_name, this->proc_addr, /* procedure details */
depth, (unsigned)stack_trace.stack.lwb-(unsigned)this);
}
print_indent(); fprintf(stderr, "--- (depth %d) ---\n", stack_trace.stack.depth);
}
}</syntaxhighlight>
'''==> stack_trace_test.c <=='''
The following code demonstrates the usage of the macros. Note that the initial and last curly brackets have been changed to BEGIN(procedure_name) and END. This is sometimes called '''macro magic''' and is unfashionable.
<syntaxhighlight lang="c">#include <stdio.h>
#include <stdlib.h>
#define STACK_TRACE_ON /* compile in these "stack_trace" routines */
#include "stack_trace.h"
void inner(int k)
BEGIN(inner)
print_indent(); printf("*** Now dump the stack ***\n");
print_stack_trace();
END
void middle(int x, int y)
BEGIN(middle)
inner(x*y);
END
void outer(int a, int b, int c)
BEGIN(outer)
middle(a+b, b+c);
END
int main()
BEGIN(main)
stack_trace.on = TRUE; /* turn on runtime tracing */
outer(2,3,5);
stack_trace.on = FALSE;
RETURN(EXIT_SUCCESS);
END</syntaxhighlight>
{{out}}
<pre>
stack_trace_test.c:19: BEGIN outer[0x80487b4], stack(depth:1, size:60)
stack_trace_test.c:14: BEGIN middle[0x8048749], stack(depth:2, size:108)
stack_trace_test.c:8: BEGIN inner[0x80486d8], stack(depth:3, size:156)
stack_trace_test.c:8: *** Now dump the stack ***
stack_trace_test.c:8: inner[0x80486d8] --- stack(depth:4, size:156) ---
stack_trace_test.c:14: middle[0x8048749] --- stack(depth:3, size:108) ---
stack_trace_test.c:19: outer[0x80487b4] --- stack(depth:2, size:60) ---
stack_trace_test.c:24: main[0x804882a] --- stack(depth:1, size:0) ---
stack_trace_test.c:8: --- (depth 4) ---
stack_trace_test.c:8: END inner[0x80486d8], stack(depth:3, size:156)
stack_trace_test.c:14: END middle[0x8048749], stack(depth:2, size:108)
stack_trace_test.c:19: END outer[0x80487b4], stack(depth:1, size:60)
</pre>
=={{header|C sharp|C#}}==
<syntaxhighlight lang="csharp">using System;
using System.Diagnostics;
class Program
{
static void Inner()
{
Console.WriteLine(new StackTrace());
}
static void Middle()
{
Inner();
}
static void Outer()
{
Middle();
}
static void Main()
{
Outer();
}
}</syntaxhighlight>
Sample output:
<syntaxhighlight lang="text">at Program.Inner()
at Program.Middle()
at Program.Outer()
at Program.Main()</syntaxhighlight>
=={{header|Clojure}}==
{{works with|Java|1.6+}}
[http://docs.oracle.com/javase/8/docs/api/java/lang/management/ThreadMXBean.html ThreadMXBean] can be used to show you the stack of all live threads.
<syntaxhighlight lang="clojure">
(doall
(map println (.dumpAllThreads (java.lang.management.ManagementFactory/getThreadMXBean) false false)))
</syntaxhighlight>
{{out}}
<pre>
#<ThreadInfo "nREPL-worker-26" Id=64 RUNNABLE
at sun.management.ThreadImpl.dumpThreads0(Native Method)
at sun.management.ThreadImpl.dumpAllThreads(ThreadImpl.java:446)
at user$eval1285.invoke(form-init6675235431801252432.clj:1)
at clojure.lang.Compiler.eval(Compiler.java:6619)
at clojure.lang.Compiler.eval(Compiler.java:6582)
at clojure.core$eval.invoke(core.clj:2852)
at clojure.main$repl$read_eval_print__6588$fn__6591.invoke(main.clj:259)
at clojure.main$repl$read_eval_print__6588.invoke(main.clj:259)
...
</pre>
=={{header|Common Lisp}}==
Line 214 ⟶ 529:
Here we use SWANK, which a component of SLIME, a Common Lisp IDE (it is the library loaded into the target Lisp system to enable interaction and remote debugging), to make use of its portable debugging facilities:
<
(lambda ()
(swank:backtrace 0 nil)))</
Here are a few lines of the result when running under [[SBCL]], the rest is omitted since it's long and boring:
<
(1 "(SB-INT:SIMPLE-EVAL-IN-LEXENV (SWANK-BACKEND:CALL-WITH-DEBUGGING-ENVIRONMENT (LAMBDA () (SWANK:BACKTRACE 0 NIL))) #<NULL-LEXENV>)")
(2 "(SWANK::EVAL-REGION \"(swank-backend:call-with-debugging-environment\\n (lambda ()\\n (swank:backtrace 0 nil)))\\n\\n\")")
(3 "((LAMBDA ()))") ...)</
Note that this is a data structure containing the backtrace, not a format intended for presentation. In [[SBCL]], executing <code>(sb-debug:backtrace 7)</code> produces output like this (run from the SLIME-REPL, which is why it still contains mentions of SWANK):
<
0: (SB-DEBUG::MAP-BACKTRACE
#<CLOSURE (LAMBDA (SB-DEBUG::FRAME)) {1193EFCD}>)[:EXTERNAL]
Line 242 ⟶ 557:
6: (SWANK::CALL-WITH-RETRY-RESTART
"Retry SLIME REPL evaluation request."
#<CLOSURE (LAMBDA ()) {1193EC4D}>)</
SBCL's backtraces consist entirely of lists of the form <code>(<var>function-name</var> <var>args...</var>)</code>.
=={{header|D}}==
Compiled with the dmd compiler using the -g switch.
{{trans|Java}}
<syntaxhighlight lang="d">import std.stdio, core.runtime;
void inner() { defaultTraceHandler.writeln; }
void middle() { inner; }
void outer() { middle; }
void main() {
outer;
"After the stack trace.".writeln;
}</syntaxhighlight>
{{out}}
<pre>0x00404FBE in core.sys.windows.stacktrace.StackTrace core.sys.windows.stacktrace.StackTrace.__ctor(uint, core.sys.windows.windows.CONTEXT*) at E:\dmd2\src\druntime\import\core\sys\windows\stacktrace.d(69)
0x00404ACB in object.Throwable.TraceInfo core.runtime.defaultTraceHandler(void*) at E:\dmd2\src\druntime\import\core\runtime.d(646)
0x0040201A in void test.inner() at E:\test.d(3)
0x0040202C in void test.middle() at E:\test.d(4)
0x00402038 in void test.outer() at E:\test.d(5)
0x00402044 in _Dmain at E:\test.d(9)
0x00409AAC in void rt.dmain2._d_run_main(int, char**, extern (C) int function(char[][])*).runAll().void __lambda1()
0x00409A7F in void rt.dmain2._d_run_main(int, char**, extern (C) int function(char[][])*).runAll()
0x00409997 in _d_run_main
0x004048D8 in main
0x0041FB2D in mainCRTStartup
0x76EED2E9 in BaseThreadInitThunk
0x77821603 in RtlInitializeExceptionChain
0x778215D6 in RtlInitializeExceptionChain
After the stack trace.</pre>
=={{header|DWScript}}==
Stack traces can be obtained from exception objects
<syntaxhighlight lang="delphi">procedure Inner;
begin
try
raise Exception.Create('');
except
on E: Exception do
PrintLn(E.StackTrace);
end;
end;
procedure Middle;
begin
Inner;
end;
procedure Outer;
begin
Middle;
end;
Outer;</syntaxhighlight>
Output:<pre>Inner [line: 4, column: 23]
Middle [line: 13, column: 4]
Outer [line: 18, column: 4]
[line: 21, column: 1]</pre>
=={{header|Elena}}==
{{trans|C#}}
ELENA 6.x :
<syntaxhighlight lang="elena">import extensions;
public singleton program
{
inner()
{
console.printLine(new CallStack())
}
middle()
{
self.inner()
}
outer()
{
self.middle()
}
// program entry point
function()
{
program.outer()
}
}</syntaxhighlight>
{{out}}
<pre>
sandbox'program.inner[1]:sandbox.l(7)
sandbox'program.middle[1]:sandbox.l(12)
sandbox'program.outer[1]:sandbox.l(17)
sandbox'program.function:#invoke:sandbox.l(23)
system'$private'entry.function:#invoke:app.l(5)
system'$private'entrySymbol#sym:app.l(44)
</pre>
=={{header|Elixir}}==
{{trans|Erlang}}
<syntaxhighlight lang="elixir">defmodule Stack_traces do
def main do
{:ok, a} = outer
IO.inspect a
end
defp outer do
{:ok, a} = middle
{:ok, a}
end
defp middle do
{:ok, a} = inner
{:ok, a}
end
defp inner do
try do
throw(42)
catch 42 -> {:ok, :erlang.get_stacktrace}
end
end
end
Stack_traces.main</syntaxhighlight>
{{out}}
<pre>
[{Stack_traces, :inner, 0, [file: 'stack_trace.exs', line: 19]},
{Stack_traces, :middle, 0, [file: 'stack_trace.exs', line: 13]},
{Stack_traces, :outer, 0, [file: 'stack_trace.exs', line: 8]},
{Stack_traces, :main, 0, [file: 'stack_trace.exs', line: 3]},
{:elixir_compiler, :dispatch_loaded, 6,
[file: 'src/elixir_compiler.erl', line: 125]},
{:elixir_lexical, :run, 3, [file: 'src/elixir_lexical.erl', line: 16]},
{:elixir_compiler, :quoted, 3, [file: 'src/elixir_compiler.erl', line: 30]},
{Code, :require_file, 2, [file: 'lib/code.ex', line: 363]}]
</pre>
=={{header|Erlang}}==
{{trans|Java}}
Stack traces only can be obtained inside a catch block. Additionally, it doesn't work for tail calls.
<syntaxhighlight lang="erlang">-module(stack_traces).
-export([main/0]).
main() ->
{ok,A} = outer(),
io:format("~p\n", [A]).
outer() ->
{ok,A} = middle(),
{ok,A}.
middle() ->
{ok,A} = inner(),
{ok,A}.
inner() ->
try throw(42) catch 42 -> {ok,erlang:get_stacktrace()} end.</syntaxhighlight>
{{out}}
<pre>[{stack_traces,inner,0,[{file,"stack_traces.erl"},{line,18}]},
{stack_traces,middle,0,[{file,"stack_traces.erl"},{line,14}]},
{stack_traces,outer,0,[{file,"stack_traces.erl"},{line,10}]},
{stack_traces,main,0,[{file,"stack_traces.erl"},{line,6}]},
{init,start_it,1,[]},
{init,start_em,1,[]}]</pre>
=={{header|F_Sharp|F#}}==
{{trans|C#}}
<syntaxhighlight lang="fsharp">open System.Diagnostics
type myClass() =
member this.inner() = printfn "%A" (new StackTrace())
member this.middle() = this.inner()
member this.outer() = this.middle()
[<EntryPoint>]
let main args =
let that = new myClass()
that.outer()
0</syntaxhighlight>
Output
<pre> at Rosetta.myClass.inner()
at Rosetta.myClass.middle()
at Rosetta.myClass.outer()
at Rosetta.main(String[] args)</pre>
=={{header|Factor}}==
This stack trace shows the listener — Factor's Read-Eval-Print-Loop. The current execution point in each call frame is indicated by <code>=></code>. Press ctrl+w in the listener to walk through the call stack one step at a time and watch how it affects the data stack. You can even step backward in most cases. This is handy for debugging.
<syntaxhighlight lang="factor">USE: prettyprint
get-callstack callstack.</syntaxhighlight>
{{out}}
<pre>
(U)
Quotation: [ set-namestack init-catchstack self quot>> call => stop ]
(O)
Word: listener-thread
(O)
Word: listener
(O)
Word: (listener)
(O)
Word: listener-step
(U)
Quotation: [
[ ~quotation~ dip swap ~quotation~ dip ] dip swap
[ call get-datastack ] dip => swap [ set-datastack ] dip
]
</pre>
=={{header|Forth}}==
In Forth, calling sequence information is kept on the Return Stack. Some Forth compilers have the word "R.S" that dumps the contents of the Return Stack - just like ".S", which dumps the contents of the Data Stack. Note this may also include stack frames, local variables and temporary values. Forth has no way of knowing which is which, because that is usually left to the programmer.
{{works with|4tH|3.60.0}}
<
\ Return stack counterpart of DEPTH
\ Note the STACK-CELLS correction is there to hide RDEPTH itself
Line 263 ⟶ 788:
BEGIN DUP WHILE ROT DUP . >R 1- REPEAT DROP
THEN ." (TORS) " DROP >R ;
[THEN]</
=={{header|Fortran}}==
Fortran provides nothing of the sort as a language feature. A given compiler may (possibly via an option) record information in the code file that when a fatal error such as divide-by-zero is caught, allows the error message to name the routine in which the error occurred, possibly identifying the source line and perhaps even the sequence of routines that were invoked to get there. Otherwise, a routine has no information whereby it might identify its caller - or for that matter, itself. Some compilers might make available special routines, but, there is no such requirement in the standard. Outside of Fortran's lack of standardised access, some systems such as TaskInfo on Windows can show a task's current call stack (updated each time TaskInfo re-samples, say every four seconds), possibly including the names of the called routines. Watching this being updated as the task runs a lengthy computation gives hints that otherwise could be provided via execution profiling and a lot more effort.
Otherwise, it is up to the programmer. For instance, on entry to ''every'' routine, <code>CALL SUBIN("''name''")</code> and on exit, ''without fail'', <code>CALL SUBOUT("''name''")</code> which routines maintain a ... stack of names, and further can count invocations, though perhaps not for heavily-used routines - trials suggest that around ten million SUBIN calls consume about a second of cpu time. Add to this the judicious use of a routine <code>CALL STATE("''activity description''")</code> similarly using a stack (the stack pointer being maintained by SUBIN/SUBOUT) not only provides interesting documentation in the source but also, should there be a disaster, <code>CALL CROAK("''dismayed message''")</code> can be used to end a run, routine CROAK of course displaying the current stack with at each level the declared activity message before the final STOP. A similar routine could be invoked to display the current stack state without a STOP as some sort of status report. With this protocol in place, the routine to present trace output can name its caller (and, the caller of that) to provide some context for the bewildering output.
Here for example is a run of such a programme, called Gnash (for New Zealand's national collection of half-hourly electricity data) that accepts certain commands and in particular a command "croak". A log of input and output is maintained, echoing what appears on the screen. Thus, the programme requests the next input after prompting "Gnash:" and that input is the command "croak" followed by some text...
<pre>
Gnash: croak Life is troubled
Goodbye, cruel world!
Routine XeqACard croaks: Life is troubled
...from XeqACard Confronting croak Life is troubled
...from Attack some input
...from Gnash Gnash gnashing
Omitted exit from level 3:XeqACard
Omitted exit from level 2:Attack
</pre>
So, Gnash has invoked ATTACK to deal with input commands, as if cards are being read. ATTACK states that it is dealing with some input (possibly from a script file but in this case the keyboard), and invokes XeqACard to do so. It states that it is confronting some text, then invokes the appropriate command handler - which invokes CROAK, which unwinds the stack. Its final act is <code>STOP "I STOP now. Farewell..." !Whatever pit I was in, I'm gone.</code> which of course is not written to the log file and unless you're using a DOS-style session, the window will be closed before you can read it.
Should a fatal error be declared by the run-time system, none of this will happen, but if while running, some unrecoverable or a should-never-happen but I'll check anyway type of problem be noted, then a possibly informative output will follow.
=={{header|FreeBASIC}}==
Code extracted from FreeBAsic Forum
[https://freebasic.net/forum/viewtopic.php?t=31371 https://freebasic.net/forum/viewtopic.php?t=31371]
<syntaxhighlight lang="vb">#include "windows.bi"
Private Function Fn2() As Long
Dim frames(0 To 60) As Any Ptr
Dim framesPtr As Any Ptr Ptr = @frames(0)
Dim hash As DWORD
Dim As Long caught = CaptureStackBackTrace(0, 61, framesPtr, @hash)
Print Using "Caught & frames using stack capture"; caught
For i As Long = 0 To caught - 1
Print Using "&) &"; caught - i; Hex(frames(i))
Next
Return caught
End Function
Private Sub Fn1(num As Ulong)
Dim As Long numFn2 = Fn2()
Print Using "Fn2 returned & with num = &"; numFn2; num
End Sub
Fn1(87)
Sleep</syntaxhighlight>
{{out}}
<pre>Caught 7 frames using stack capture
7) 4016FE
6) 40185E
5) 4015BA
4) 4013B4
3) 40150B
2) 7FFBD6AC7614
1) 7FFBD7B226A1
Fn2 returned 7 with num = 87</pre>
=={{header|Go}}==
<syntaxhighlight lang="go">package main
import (
"fmt"
"runtime"
)
func main() {
stackTrace := make([]byte, 1024)
n := runtime.Stack(stackTrace, true)
stackTrace = stackTrace[:n]
fmt.Printf("%s\n", stackTrace)
fmt.Printf("(%d bytes)\n", len(stackTrace))
}</syntaxhighlight>
outputs:
<pre>
goroutine 16 [running]:
main.main()
/tmpfs/gosandbox-efa5a722_5cfcad46_bebc14b4_0486dec5_bd9e34fc/prog.go:10 +0xa0
goroutine 19 [runnable]:
runfinq()
/tmp/sandbox/go/src/pkg/runtime/mgc0.c:2606
runtime.goexit()
/tmp/sandbox/go/src/pkg/runtime/proc.c:1445
(259 bytes)
</pre>
=={{header|Groovy}}==
Solution:
<syntaxhighlight lang="groovy">def rawTrace = { Thread.currentThread().stackTrace }</syntaxhighlight>
Test: (demonstrates, among other things, continued execution after generating stack trace)
<syntaxhighlight lang="groovy">def trace = rawTrace().collect {
def props = it.properties
def keys = (it.properties.keySet() - (new Object().properties.keySet()))
props.findAll{ k, v -> k in keys }
}
def propNames = trace[0].keySet().sort()
def propWidths = propNames.collect { name -> [name, trace.collect{ it[name].toString() }].flatten()*.size().max() }
propNames.eachWithIndex{ name, i -> printf("%-${propWidths[i]}s ", name) }; println ''
propWidths.each{ width -> print('-' * width + ' ') }; println ''
trace.each {
propNames.eachWithIndex{ name, i -> printf("%-${propWidths[i]}s ", it[name].toString()) }; println ''
}</syntaxhighlight>
Output:
<pre style="height:45ex;overflow:scroll;">className fileName lineNumber methodName nativeMethod
----------------------------------------------------------------- --------------------------------- ---------- ------------------------------- ------------
java.lang.Thread Thread.java 1479 getStackTrace false
sun.reflect.NativeMethodAccessorImpl NativeMethodAccessorImpl.java -2 invoke0 true
sun.reflect.NativeMethodAccessorImpl NativeMethodAccessorImpl.java 39 invoke false
sun.reflect.DelegatingMethodAccessorImpl DelegatingMethodAccessorImpl.java 25 invoke false
java.lang.reflect.Method Method.java 597 invoke false
org.codehaus.groovy.reflection.CachedMethod CachedMethod.java 90 invoke false
groovy.lang.MetaMethod MetaMethod.java 233 doMethodInvoke false
groovy.lang.MetaClassImpl$GetBeanMethodMetaProperty MetaClassImpl.java 3465 getProperty false
org.codehaus.groovy.runtime.callsite.GetEffectivePojoPropertySite GetEffectivePojoPropertySite.java 61 getProperty false
org.codehaus.groovy.runtime.callsite.AbstractCallSite AbstractCallSite.java 227 callGetProperty false
ConsoleScript38$_run_closure1 ConsoleScript38 1 doCall false
sun.reflect.NativeMethodAccessorImpl NativeMethodAccessorImpl.java -2 invoke0 true
sun.reflect.NativeMethodAccessorImpl NativeMethodAccessorImpl.java 39 invoke false
sun.reflect.DelegatingMethodAccessorImpl DelegatingMethodAccessorImpl.java 25 invoke false
java.lang.reflect.Method Method.java 597 invoke false
org.codehaus.groovy.reflection.CachedMethod CachedMethod.java 90 invoke false
groovy.lang.MetaMethod MetaMethod.java 233 doMethodInvoke false
org.codehaus.groovy.runtime.metaclass.ClosureMetaClass ClosureMetaClass.java 272 invokeMethod false
groovy.lang.MetaClassImpl MetaClassImpl.java 885 invokeMethod false
org.codehaus.groovy.runtime.callsite.PogoMetaClassSite PogoMetaClassSite.java 66 callCurrent false
org.codehaus.groovy.runtime.callsite.CallSiteArray CallSiteArray.java 46 defaultCallCurrent false
org.codehaus.groovy.runtime.callsite.AbstractCallSite AbstractCallSite.java 133 callCurrent false
org.codehaus.groovy.runtime.callsite.AbstractCallSite AbstractCallSite.java 141 callCurrent false
ConsoleScript38$_run_closure1 ConsoleScript38 -1 doCall false
sun.reflect.NativeMethodAccessorImpl NativeMethodAccessorImpl.java -2 invoke0 true
sun.reflect.NativeMethodAccessorImpl NativeMethodAccessorImpl.java 39 invoke false
sun.reflect.DelegatingMethodAccessorImpl DelegatingMethodAccessorImpl.java 25 invoke false
java.lang.reflect.Method Method.java 597 invoke false
org.codehaus.groovy.reflection.CachedMethod CachedMethod.java 90 invoke false
groovy.lang.MetaMethod MetaMethod.java 233 doMethodInvoke false
org.codehaus.groovy.runtime.metaclass.ClosureMetaClass ClosureMetaClass.java 272 invokeMethod false
groovy.lang.MetaClassImpl MetaClassImpl.java 885 invokeMethod false
org.codehaus.groovy.runtime.callsite.PogoMetaClassSite PogoMetaClassSite.java 39 call false
org.codehaus.groovy.runtime.callsite.CallSiteArray CallSiteArray.java 42 defaultCall false
org.codehaus.groovy.runtime.callsite.AbstractCallSite AbstractCallSite.java 108 call false
org.codehaus.groovy.runtime.callsite.AbstractCallSite AbstractCallSite.java 112 call false
ConsoleScript38 ConsoleScript38 3 run false
groovy.lang.GroovyShell GroovyShell.java 266 runScriptOrMainOrTestOrRunnable false
groovy.lang.GroovyShell GroovyShell.java 517 run false
groovy.lang.GroovyShell GroovyShell.java 172 run false
groovy.lang.GroovyShell$run null -1 call false
groovy.ui.Console$_runScriptImpl_closure16 Console.groovy 910 doCall false
sun.reflect.GeneratedMethodAccessor232 null -1 invoke false
sun.reflect.DelegatingMethodAccessorImpl DelegatingMethodAccessorImpl.java 25 invoke false
java.lang.reflect.Method Method.java 597 invoke false
org.codehaus.groovy.reflection.CachedMethod CachedMethod.java 90 invoke false
groovy.lang.MetaMethod MetaMethod.java 233 doMethodInvoke false
org.codehaus.groovy.runtime.metaclass.ClosureMetaClass ClosureMetaClass.java 272 invokeMethod false
groovy.lang.MetaClassImpl MetaClassImpl.java 885 invokeMethod false
org.codehaus.groovy.runtime.callsite.PogoMetaClassSite PogoMetaClassSite.java 66 callCurrent false
org.codehaus.groovy.runtime.callsite.AbstractCallSite AbstractCallSite.java 141 callCurrent false
groovy.ui.Console$_runScriptImpl_closure16 Console.groovy -1 doCall false
sun.reflect.GeneratedMethodAccessor231 null -1 invoke false
sun.reflect.DelegatingMethodAccessorImpl DelegatingMethodAccessorImpl.java 25 invoke false
java.lang.reflect.Method Method.java 597 invoke false
org.codehaus.groovy.reflection.CachedMethod CachedMethod.java 90 invoke false
groovy.lang.MetaMethod MetaMethod.java 233 doMethodInvoke false
org.codehaus.groovy.runtime.metaclass.ClosureMetaClass ClosureMetaClass.java 272 invokeMethod false
groovy.lang.MetaClassImpl MetaClassImpl.java 885 invokeMethod false
groovy.lang.Closure Closure.java 405 call false
groovy.lang.Closure Closure.java 399 call false
groovy.lang.Closure Closure.java 483 run false
java.lang.Thread Thread.java 662 run false</pre>
==Icon and {{header|Unicon}}==
This Icon solution uses Unicon extensions. An Icon only version has not been provided.
{{libheader|Unicon Code Library}}
[http://tapestry.tucson.az.us/unilib/pack_Utils.html the following code for buildStackTrace in Utils is taken verbatim and shown below the main program]
<syntaxhighlight lang="unicon">
import Utils # for buildStackTrace
procedure main()
g()
write()
f()
end
procedure f()
g()
end
procedure g()
# Using 1 as argument omits the trace of buildStackTrace itself
every write("\t",!buildStackTrace(1))
end</syntaxhighlight>
<syntaxhighlight lang="unicon">#<p>
# Compute the current stack trace. Starting at level <i>n</i> above
# the current procedure. Here, <i>n</i> defaults to 0, which will
# include this procedure in the stack trace.
# <i>ce</i> defaults to ¤t.
# <i>This only works with newer versions of Unicon!</i>
# <[generates the stacktrace from current call back to first
# in the co-expression]>
#</p>
procedure buildStackTrace(n:0, # starting distance from this call
ce # co-expr to trace stack in [¤t]
)
local L
/ce := ¤t
L := []; n -:= 1
while pName := image(proc(ce, n+:=1)) do {
fName := keyword("&file",ce,n) | "no file name"
fLine := keyword("&line",ce,n) | "no line number"
put(L, pName||" ["||fName||":"||fLine||"]" )
}
return L
end</syntaxhighlight>
The output of this example is:
<pre>
procedure g [Stacktrace.icn:13]
procedure main [Stacktrace.icn:2]
procedure g [Stacktrace.icn:13]
procedure f [Stacktrace.icn:8]
procedure main [Stacktrace.icn:4]
</pre>
=={{header|J}}==
Line 270 ⟶ 1,024:
To enable suspension and record subsequent stack frames:
<syntaxhighlight lang
To retrieve a current stack trace:
<syntaxhighlight lang
See also: http://www.jsoftware.com/help/dictionary/dx013.htm
Example:
<syntaxhighlight lang="j"> f=:g
g=:13!:13 bind ''
f 7 NB. empty stack trace because debugging has not been enabled
13!:0]1
f 7
┌─┬─┬─┬─┬─────────────┬┬───┬──┬─┐
│g│0│0│3│13!:13@(''"_)││┌─┐│ │ │
│ │ │ │ │ │││7││ │ │
│ │ │ │ │ ││└─┘│ │ │
├─┼─┼─┼─┼─────────────┼┼───┼──┼─┤
│f│0│0│3│g ││┌─┐│ │ │
│ │ │ │ │ │││7││ │ │
│ │ │ │ │ ││└─┘│ │ │
└─┴─┴─┴─┴─────────────┴┴───┴──┴─┘</syntaxhighlight>
Technical note: the stack trace is not displayed, here, until after the stack has been discarded. This is because we have returned the stack trace as a result and relied on J's implicit display of the result of an expression to display the stack trace.
=={{header|Java}}==
{{works with|Java|1.5+}}
<
public static void printStackTrace() {
StackTraceElement[] elems = Thread.currentThread().getStackTrace();
Line 289 ⟶ 1,062:
}
}
}</
Demonstration code:
<
static void inner() {
StackTracer.printStackTrace();
Line 304 ⟶ 1,077:
outer();
}
}</
Output:
<pre>Stack trace:
Line 315 ⟶ 1,088:
There is no standard way to do this, but some implementations provide it.<br />
{{works with|Firefox}}
<
throw new Error;
} catch(e) {
alert(e.stack);
}</
The following version works in many browsers but it infinitely loops when there is recursion:
<
var stack = "Stack trace:";
for (var f = arguments.callee // current function
Line 336 ⟶ 1,103:
alert(stack);
}
foo();</
=={{header|
{{works with|Julia|0.6}}
<syntaxhighlight lang="julia">f() = g()
g() = println.(stacktrace())
f()</syntaxhighlight>
{{out}}
<pre>g() at Stack_traces.jl:5
f() at Stack_traces.jl:4
include_string(::String, ::String) at loading.jl:515
include_string(::Module, ::String, ::String) at Compat.jl:464
(::Atom.##57#60{String,String})() at eval.jl:74
withpath(::Atom.##57#60{String,String}, ::String) at utils.jl:30
withpath(::Function, ::String) at eval.jl:38
macro expansion at eval.jl:72 [inlined]
(::Atom.##56#59{Dict{String,Any}})() at task.jl:80</pre>
=={{header|Kotlin}}==
<syntaxhighlight lang="scala">// version 1.1.2 (stacktrace.kt which compiles to StacktraceKt.class)
fun myFunc() {
println(Throwable().stackTrace.joinToString("\n"))
}
fun main(args:Array<String>) {
myFunc()
println("\nContinuing ... ")
}</syntaxhighlight>
{{out}}
<pre>
StacktraceKt.myFunc(stacktrace.kt:4)
StacktraceKt.main(stacktrace.kt:8)
Continuing ...
</pre>
=={{header|Lang}}==
<syntaxhighlight lang="lang">
# fn.getStackTrace() returns a text-based stack trace
fp.printStackTrace = () -> fn.println(fn.getStackTrace())
# Example
fp.f1 = () -> {
fn.println(F1:)
fp.printStackTrace()
}
fp.f2 = () -> {
fn.println(F2:)
fp.printStackTrace()
fp.f1()
}
fp.f2()
fn.combA0(fp.f2)
# Partially called combinator functions' names are represented as "<comb...-func(...)>"
fn.combA(fn.combC(fn.combAE(), x), fp.f2)
</syntaxhighlight>
{{out}}
The file paths were redacted. If ":x" is outputted as the line number, no line number information is available (e.g. If Lang is implemented with an interpreter, predefined functions are written in the host language)
<pre>
F2:
at "[redacted]:x" in function "getStackTrace"
at "[redacted]:2" in function "fp.printStackTrace"
at "[redacted]:11" in function "fp.f2"
at "[redacted]:14" in function "main"
F1:
at "[redacted]:x" in function "getStackTrace"
at "[redacted]:2" in function "fp.printStackTrace"
at "[redacted]:7" in function "fp.f1"
at "[redacted]:12" in function "fp.f2"
at "[redacted]:14" in function "main"
F2:
at "[redacted]:x" in function "getStackTrace"
at "[redacted]:2" in function "fp.printStackTrace"
at "[redacted]:11" in function "fp.f2"
at "[redacted]:x" in function "combA0"
at "[redacted]:16" in function "main"
F1:
at "[redacted]:x" in function "getStackTrace"
at "[redacted]:2" in function "fp.printStackTrace"
at "[redacted]:7" in function "fp.f1"
at "[redacted]:12" in function "fp.f2"
at "[redacted]:x" in function "combA0"
at "[redacted]:16" in function "main"
F2:
at "[redacted]:x" in function "getStackTrace"
at "[redacted]:2" in function "fp.printStackTrace"
at "[redacted]:11" in function "fp.f2"
at "[redacted]:x" in function "<combAE-func()>"
at "[redacted]:x" in function "<combC-func(<combAE-func()>, <arg>)>"
at "[redacted]:x" in function "combA"
at "[redacted]:19" in function "main"
F1:
at "[redacted]:x" in function "getStackTrace"
at "[redacted]:2" in function "fp.printStackTrace"
at "[redacted]:7" in function "fp.f1"
at "[redacted]:12" in function "fp.f2"
at "[redacted]:x" in function "<combAE-func()>"
at "[redacted]:x" in function "<combC-func(<combAE-func()>, <arg>)>"
at "[redacted]:x" in function "combA"
at "[redacted]:19" in function "main"
</pre>
=={{header|Lasso}}==
By default Lasso tracks the file path, line and column numbers. You can create a trace method to track type and method names illustrated below or use one of the public libraries like L-Debug [https://github.com/zeroloop/l-debug].
<syntaxhighlight lang="lasso">// Define our own trace method
define trace => {
local(gb) = givenblock
// Set a depth counter
var(::_tracedepth)->isnota(::integer) ? $_tracedepth = 0
handle => {$_tracedepth--}
// Only output when supplied a capture
#gb ? stdoutnl(
// Indent
('\t' * $_tracedepth++) +
// Type + Method
#gb->self->type + '.' + #gb->calledname +
// Call site file
': ' + #gb->home->callsite_file +
// Line number and column number
' (line '+#gb->home->callsite_line + ', col ' + #gb->home->callsite_col +')'
)
return #gb()
}</syntaxhighlight>
;Use Trace:
<syntaxhighlight lang="lasso">define stackexample => type {
public oncreate => trace => { return self }
public inner => trace => { }
public middle => trace => { .inner }
public outer => trace => { .middle }
}
stackexample->outer</syntaxhighlight>
{{out}}
<pre>stackexample.oncreate: adminapp_lasso_runner_thread (line 2, col 24)
stackexample.outer: adminapp_lasso_runner_thread (line 5, col 21)
stackexample.middle: adminapp_lasso_runner_thread (line 4, col 22)
stackexample.inner: adminapp_lasso_runner_thread (line 3, col 21)</pre>
=={{header|Lua}}==
<syntaxhighlight lang="lua">function Inner( k )
print( debug.traceback() )
print "Program continues..."
end
function Middle( x, y )
Inner( x+y )
end
function Outer( a, b, c )
Middle( a*b, c )
end
Outer( 2, 3, 5 )</syntaxhighlight>
<pre>stack traceback:
./prog:4: in function 'Inner'
./prog:9: in function 'Middle'
./prog:13: in function 'Outer'
./prog:16: in main chunk
[C]: ?
Program continues...</pre>
=={{header|Mathematica}}/{{header|Wolfram Language}}==
Built-in function Stack does the task, example I:
<
prints, gives back:
<
f[g[1, 2]]</
Example II:
<
prints, gives back:
<
f[g[1, 2]]</
Related and similar functions are: Trace, TracePrint, TraceScan,TraceDialog, Monitor, StackInhibit, StackBegin, StackComplete. In the manual look for 'guide/SymbolicExecutionHistory'.
=={{header|Nanoquery}}==
__calls__ contains a list that represents a trace of calls that have been made.
<syntaxhighlight lang="nanoquery">def print_stack()
global __calls__
println "stack trace:"
for i in range(len(__calls__) - 2, 0)
println "\t" + __calls__[i]
end
end
print_stack()
println
for i in range(1, 1)
print_stack()
end
println
println "The program would continue."</syntaxhighlight>
{{out}}
<pre>stack trace:
<global>:10
stack trace:
<for>:1
<global>:13
The program would continue.</pre>
=={{header|NetRexx}}==
{{trans|Java}}
<syntaxhighlight lang="netrexx">/* NetRexx */
options replace format comments java crossref symbols nobinary
class RStackTraces
method inner() static
StackTracer.printStackTrace()
method middle() static
inner()
method outer() static
middle()
method main(args = String[]) public static
outer()
class RStackTraces.StackTracer
method printStackTrace() public static
elems = Thread.currentThread().getStackTrace()
say 'Stack trace:'
j_ = 2
loop i_ = elems.length - 1 to 2 by -1
say ''.left(j_) || elems[i_].getClassName()'.'elems[i_].getMethodName()
j_ = j_ + 2
end i_
</syntaxhighlight>
'''Output:'''
<pre>
Stack trace:
RStackTraces.main
RStackTraces.outer
RStackTraces.middle
RStackTraces.inner
</pre>
=={{header|Nim}}==
In (normal) debug builds stacktraces are enabled, while in release builds stacktraces are disabled by default, but can be enabled like this: <code>nim c -d:release --stacktrace:on --linetrace:on file.nim</code>
<syntaxhighlight lang="nim">proc g() =
# Writes the current stack trace to stderr.
writeStackTrace()
# Or fetch the stack trace entries for the current stack trace:
echo "----"
for e in getStackTraceEntries():
echo e.filename, "@", e.line, " in ", e.procname
proc f() =
g()
f()</syntaxhighlight>
{{out}}
For a release build:
<pre>Traceback (most recent call last)
stack_traces.nim(12) stack_traces
stack_traces.nim(10) f
stack_traces.nim(3) g
----
stack_traces.nim@12 in stack_traces
stack_traces.nim@10 in f
stack_traces.nim@6 in g
</pre>
In a debug build the stacktrace contains the full path to the source.
=={{header|Objective-C}}==
<syntaxhighlight lang="objc">#include <execinfo.h>
void *frames[128];
int len = backtrace(frames, 128);
char **symbols = backtrace_symbols(frames, len);
for (int i = 0; i < len; ++i) {
NSLog(@"%s", symbols[i]);
}
free(symbols);</syntaxhighlight>
Or in Mac OS X 10.6+:
<syntaxhighlight lang="objc">NSArray *symbols = [NSThread callStackSymbols];
for (NSString *symbol in symbols) {
NSLog(@"%@", symbol);
}</syntaxhighlight>
=={{header|OCaml}}==
{{works with|OCaml|3.11+}}
<
let () =
Line 360 ⟶ 1,411:
prerr_endline(Printexc.to_string e);
Printexc.print_backtrace stderr;
;;</
outputs:
Line 370 ⟶ 1,421:
export OCAMLRUNPARAM='b'
Then the code doesn't need
<
let () =
let _ = div 3 0 in ()
;;</
outputs:
Fatal error: exception Division_by_zero
Raised at file "test.ml", line 4, characters 10-17
=={{header|Oforth}}==
Stack trace is only available :
1) When an exception is raised
2) And when oforth debug mode is set, using --D command line option.
Otherwise no stack trace is available nor printed.
<syntaxhighlight lang="oforth">: f1 Exception throw("An exception") ;
Integer method: f2 self f1 ;
: f3 f2 ;
: f4 f3 ;
10 f4</syntaxhighlight>
{{out}}
<pre>
[1:interpreter] Exception : An exception
Into Method #throw self = (Exception) An exception
Into Method #throw self = (Class) Exception
Into Function #f1
Into Method #f2 self = (Integer) 10
Into Function #f3
</pre>
=={{header|OxygenBasic}}==
<syntaxhighlight lang="oxygenbasic">
'32bit x86
static string Report
macro ReportStack(n)
'===================
'
scope
'
static sys stack[0X100],stackptr,e
'
'CAPTURE IMAGE OF UP TO 256 ENTRIES
'
'
mov eax,n
cmp eax,0x100
(
jle exit
mov eax,0x100 'UPPER LIMIT
)
mov e,eax
mov stackptr,esp
lea edx,stack
mov ecx,e
mov esi,esp
(
mov eax,[esi]
mov [edx],eax
add esi,4
add edx,4
dec ecx
jg repeat
)
sys i
string cr=chr(13)+chr(10), tab=chr(9)
'
for i=1 to e
report+=hex(stackptr+(i-1)*4,8) tab hex(i-1,2) tab hex(stack[i],8) cr
next
'
end scope
'
end macro
'====
'TEST
'====
function foo()
'=============
push 0x44556677
push 0x33445566
push 0x22334455
push 0x11223344
ReportStack(8)
end function
Report+="Trace inside foo
"
foo()
print report
'putfile "s.txt",Report
/*
RESULT:
Trace inside foo
0017FE00 00 11223344
0017FE04 01 22334455
0017FE08 02 33445566
0017FE0C 03 44556677
0017FE10 04 005EAB1C
0017FE14 05 0017FE40
0017FE18 06 10002D5F
0017FE1C 07 00000000
*/
</syntaxhighlight>
=={{header|Oz}}==
System exceptions contain the current stack at the nested feature <code>debug.stack</code>. For example:
<
proc {Test}
_ = 1 div 0
Line 391 ⟶ 1,553:
catch E then
{Inspect E}
end</
Output:
[[File:Oz_stacktrace1.png|center|Stack trace of a system exception in Oz.]]
Line 398 ⟶ 1,560:
To access the stack trace directly, you can use the undocumented internal Debug module. Its <code>getTaskStack</code> function takes a thread, a depth value and a boolean "verbose" flag. It returns a list of stack frames. Example:
<
\switch +controlflowinfo
Line 412 ⟶ 1,574:
end
in
{F}</
Output:
[[File:Oz_stacktrace2.png|center|Stack trace created by the Debug module.]]
=={{header|PascalABC.NET}}==
<syntaxhighlight lang="perl">
procedure qqq;
begin
var st := new System.Diagnostics.StackTrace();
Print(st);
end;
procedure ppp;
begin
qqq;
end;
begin
ppp
end.
</syntaxhighlight>
{{out}}
<pre>
at Rosetta_StackTrace.Program.qqq()
at Rosetta_StackTrace.Program.ppp()
at Rosetta_StackTrace.Program.$Main()
at Rosetta_StackTrace.Program.Main()
</pre>
=={{header|Perl}}==
<
sub g {cluck 'Hello from &g';}
sub f {g;}
f;</
This prints:
Line 430 ⟶ 1,619:
main::g() called at Print a Stack Trace line 4
main::f() called at Print a Stack Trace line 6</pre>
=={{header|Phix}}==
There no standard method of obtaining a stack trace mid-run (as yet, non-fatally that is), but we can quickly cobble something together:
<!--<syntaxhighlight lang="phix">(notonline)-->
<span style="color: #008080;">constant</span> <span style="color: #000000;">W</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">machine_word</span><span style="color: #0000FF;">(),</span>
<span style="color: #0000FF;">{</span><span style="color: #000000;">RTN</span><span style="color: #0000FF;">,</span><span style="color: #000000;">PREVEBP</span><span style="color: #0000FF;">}</span> <span style="color: #0000FF;">=</span> <span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">W</span><span style="color: #0000FF;">=</span><span style="color: #000000;">4</span><span style="color: #0000FF;">?{</span><span style="color: #000000;">8</span><span style="color: #0000FF;">,</span><span style="color: #000000;">20</span><span style="color: #0000FF;">}:{</span><span style="color: #000000;">16</span><span style="color: #0000FF;">,</span><span style="color: #000000;">40</span><span style="color: #0000FF;">})</span>
<span style="color: #008080;">procedure</span> <span style="color: #000000;">show_stack</span><span style="color: #0000FF;">()</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">symtab</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">symtabN</span>
<span style="color: #004080;">integer</span> <span style="color: #000000;">rtn</span>
<span style="color: #004080;">atom</span> <span style="color: #000000;">prev_ebp</span>
#ilASM{
[32]
lea edi,[symtab]
call :%opGetST -- [edi]=symtab (ie our local:=the real symtab)
mov edi,[ebp+20] -- prev_ebp
mov eax,[edi+8] -- calling routine no
mov [rtn],eax
mov eax,edi
lea edi,[prev_ebp]
call :%pStoreMint
[64]
lea rdi,[symtab]
call :%opGetST -- [rdi]=symtab (ie our local:=the real symtab)
mov rdi,[rbp+40] -- prev_ebp
mov rax,[rdi+16] -- calling routine no
mov [rtn],rax
mov rax,rdi
lea rdi,[prev_ebp]
call :%pStoreMint
[]
}
<span style="color: #008080;">while</span> <span style="color: #000000;">rtn</span><span style="color: #0000FF;">!=</span><span style="color: #000000;">21</span> <span style="color: #008080;">do</span> <span style="color: #000080;font-style:italic;">-- (T_maintls, main top level routine, always present)</span>
<span style="color: #000000;">symtabN</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">symtab</span><span style="color: #0000FF;">[</span><span style="color: #000000;">rtn</span><span style="color: #0000FF;">]</span>
<span style="color: #0000FF;">?</span><span style="color: #000000;">symtabN</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]</span>
<span style="color: #000000;">prev_ebp</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">peekNS</span><span style="color: #0000FF;">(</span><span style="color: #000000;">prev_ebp</span><span style="color: #0000FF;">+</span><span style="color: #000000;">PREVEBP</span><span style="color: #0000FF;">,</span><span style="color: #000000;">W</span><span style="color: #0000FF;">,</span><span style="color: #000000;">0</span><span style="color: #0000FF;">)</span>
<span style="color: #000000;">rtn</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">peekNS</span><span style="color: #0000FF;">(</span><span style="color: #000000;">prev_ebp</span><span style="color: #0000FF;">+</span><span style="color: #000000;">RTN</span><span style="color: #0000FF;">,</span><span style="color: #000000;">W</span><span style="color: #0000FF;">,</span><span style="color: #000000;">0</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">procedure</span>
<span style="color: #008080;">procedure</span> <span style="color: #000000;">three</span><span style="color: #0000FF;">(</span><span style="color: #004080;">bool</span> <span style="color: #000000;">die</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">die</span> <span style="color: #008080;">then</span>
<span style="color: #0000FF;">?</span><span style="color: #000000;">9</span><span style="color: #0000FF;">/</span><span style="color: #000000;">0</span>
<span style="color: #008080;">else</span>
<span style="color: #000000;">show_stack</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;">procedure</span>
<span style="color: #008080;">procedure</span> <span style="color: #000000;">two</span><span style="color: #0000FF;">(</span><span style="color: #004080;">bool</span> <span style="color: #000000;">die</span><span style="color: #0000FF;">)</span>
<span style="color: #000000;">three</span><span style="color: #0000FF;">(</span><span style="color: #000000;">die</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">procedure</span>
<span style="color: #008080;">procedure</span> <span style="color: #000000;">one</span><span style="color: #0000FF;">(</span><span style="color: #004080;">bool</span> <span style="color: #000000;">die</span><span style="color: #0000FF;">)</span>
<span style="color: #000000;">two</span><span style="color: #0000FF;">(</span><span style="color: #000000;">die</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">procedure</span>
<span style="color: #000000;">one</span><span style="color: #0000FF;">(</span><span style="color: #000000;">0</span><span style="color: #0000FF;">)</span>
<span style="color: #0000FF;">?</span><span style="color: #7060A8;">routine_id</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"dummy"</span><span style="color: #0000FF;">)</span> <span style="color: #000080;font-style:italic;">-- see note below</span>
<span style="color: #000000;">one</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">)</span>
<!--</syntaxhighlight>-->
During compilation, the symbol table entries hold an integer ternary tree index rather than a string name, and normally
things are left like that during interpretation (the proper string names are always written out when an executable is
created) unless and until a fatal error occurs, or the compiler has evidence that they might be needed, such as that
unresolved routine_id("dummy"). The -1 in the output below is that call failing to find any such routine.
{{Out}}
<pre>
"three"
"two"
"one"
-1
C:\Program Files (x86)\Phix\e01.exw:59 in procedure three()
attempt to divide by 0
die = 1
... called from C:\Program Files (x86)\Phix\e01.exw:66 in procedure two()
die = 1
... called from C:\Program Files (x86)\Phix\e01.exw:70 in procedure one()
die = 1
... called from C:\Program Files (x86)\Phix\e01.exw:75
Global & Local Variables
--> see C:\Program Files (x86)\Phix\ex.err
Press Enter...
</pre>
The first half (up to the -1) is the output from show_stack_trace(), the rest is standard fatal error diagnostics.<br>
For more details of how the latter is actually produced, refer to builtins\VM\pDiagN.e - in particular the conversion of
raw addresses into source code line numbers is not trivial (and not worth trying to replicate here). In fact I didn't just
type all that #ilASM gunk above in, but instead copied it from other source files in builtins\VM.
Alternatively, but only when interpreting (whereas the above works as shown both when interpreting and pre-compiled), the debugger is
started with the much saner
<!--<syntaxhighlight lang="phix">-->
<span style="color: #008080;">trace</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">)</span>
<!--</syntaxhighlight>-->
though as yet it offers no means of examining the stack trace (resume-ably), the above suggests it should be relative easy to add.
=={{header|PHP}}==
<
class StackTraceDemo {
static function inner() {
Line 446 ⟶ 1,732:
StackTraceDemo::outer();
?></
<pre>#0 StackTraceDemo::inner() called at [/home/cweiske/Dev/cvs/test/php-stacktrace.php:7]
#1 StackTraceDemo::middle() called at [/home/cweiske/Dev/cvs/test/php-stacktrace.php:10]
#2 StackTraceDemo::outer() called at [/home/cweiske/Dev/cvs/test/php-stacktrace.php:14]</pre>
=={{header|PicoLisp}}==
PicoLisp doesn't keep full backtrace information at runtime. This is for performance reasons. However, existing variable bindings (environments) can be inspected with the '[http://software-lab.de/doc/refE.html#env env]' function, so this can be used to build your own stack frames.
The following is analog to (though simpler than) the built-in '[http://software-lab.de/doc/refT.html#trace trace]' mechanism. The function '$$' (corresponds to '[http://software-lab.de/doc/ref_.html#$ $]' for tracing) is inserted by 'stackAll' into every function and method definition (corresponds to '[http://software-lab.de/doc/refT.html#traceAll traceAll]'). Then, when stopping at a '[http://software-lab.de/doc/refD.html#debug debug]' breakpoint or an error handler, 'dumpStack' can be used to inspect the stack contents.
As this mechanism uses 'let' to hold the stack frames, it is robust also across catch/throw, coroutines and error handling.
<syntaxhighlight lang="picolisp">(off "Stack")
(de $$ "Prg"
(let "Stack" (cons (cons (car "Prg") (env)) "Stack") # Build stack frame
(set "Stack"
(delq (asoq '"Stack" (car "Stack")) # Remove self-created entries
(delq (asoq '"Prg" (car "Stack"))
(car "Stack") ) ) )
(run (cdr "Prg")) ) ) # Run body
(de stackAll (Excl)
(let *Dbg NIL
(for "X" (all)
(or
(memq "X" Excl)
(memq "X" '($$ @ @@ @@@))
(= `(char "*") (char "X"))
(cond
((= `(char "+") (char "X"))
(for "Y" (pair (val "X"))
(and
(pair "Y")
(fun? (cdr "Y"))
(unless (== '$$ (caaddr "Y"))
(con (cdr "Y")
(list
(cons '$$ (cons (car "Y" "X") (cddr "Y"))) ) ) ) ) ) )
((pair (getd "X"))
(let "Y" @
(unless (== '$$ (caadr "Y"))
(con "Y"
(list (cons '$$ "X" (cdr "Y"))) ) ) ) ) ) ) ) ) )
(de dumpStack ()
(more (reverse (cdr "Stack")))
T )</syntaxhighlight>
Test:
<syntaxhighlight lang="picolisp">(de foo (A B)
(let C 3
(bar (inc 'A) (inc 'B) (inc 'C)) ) )
(de bar (A D E)
(let (A 7 B 8 C 9)
(! println A B C) ) ) # Set a breakpoint before (println A B C)
(stackAll)</syntaxhighlight>
<pre>: (foo 1 2) # Call 'foo'
(println A B C) # Stopped at breakpoint in 'bar'
! (dumpStack) # Dump stack history
(foo (A . 1) (B . 2) (@ . T)) # Hit <enter> on each line to continue
(bar (B . 3) (C . 4) (A . 2) (D . 3) (E . 4) (@ . T))
-> T
! # Hit <enter> to continue execution
7 8 9 # Output of (println A B C)
-> 9
:</pre>
=={{header|PL/I}}==
<syntaxhighlight lang="pl/i">
/* The SNAP option in the ON statement is sufficient to obtain */
/* a traceback. The SYSTEM option specifies that standard */
/* system action is to occur, which resume execution after the */
/* SIGNAL statement. */
on condition(traceback) snap system;
...
signal condition(traceback);
</syntaxhighlight>
=={{header|PureBasic}}==
The [http://www.purebasic.com/documentation/debugger/showcallstack.html ShowCallstack()]command opens a interactive display allowing viewing of the procedures in the calling path an all their local variables.
<syntaxhighlight lang="purebasic">Procedure Three()
a=7
ShowCallstack()
CallDebugger
EndProcedure
Procedure Two()
a=4
Three()
EndProcedure
Procedure One()
a=2
Two()
EndProcedure
One()</syntaxhighlight>
=={{header|Python}}==
See the [http://docs.python.org/library/traceback.html traceback] module
<
def f(): return g()
def g(): traceback.print_stack()
f()</
Sample output from a session in the Idle IDE:
Line 475 ⟶ 1,855:
def g(): traceback.print_stack()
</pre>
=={{header|Quackery}}==
Quackery has two system stacks, the call or return stack and a data stack. The words <code>echoreturn</code> and <code>echostack</code> display the current state of them. Each call to a word or nest places two entries on the return stack, a pointer to the word or nest, and an index into that word or nest. These are displayed as the name of the word, or <code>[...]</code> for an unnamed nest, and the index into the word or nest as an integer. Pairs of entries are displayed wrapped in braces, e.g. <code>{shell 5}</code>.
This is illustrated with a Quackery shell dialogue. The Quackery shell is written in Quackery, and as can be seen, occupies five pairs of entries on the return stack. After each interaction with the user the data stack is automatically displayed. Here the user opens the Quackery shell, displays the return stack, defines a naive recursive Fibonacci word that displays the return and data stack at the start of each call, and uses it to compute and display the fifth Fibonacci number (5).
<pre> > quackery
Welcome to Quackery.
Enter "leave" to leave the shell.
Building extensions.
/O> echoreturn
...
{[...] 0} {quackery 1} {[...] 11} {shell 5} {quackery 1} {[...] 0}
Stack empty.
/O> [ cr echoreturn
... cr echostack
... dup 2 < if done
... dup 1 - swap 2 -
... recurse swap recurse + ] is fib
...
Stack empty.
/O> 5 fib echo
...
{[...] 0} {quackery 1} {[...] 11} {shell 5} {quackery 1} {[...] 1} {fib 1}
Stack: 5
{[...] 0} {quackery 1} {[...] 11} {shell 5} {quackery 1} {[...] 1} {fib 15} {recurse 1} {fib 1}
Stack: 4 3
{[...] 0} {quackery 1} {[...] 11} {shell 5} {quackery 1} {[...] 1} {fib 15} {recurse 1} {fib 15} {recurse 1} {fib 1}
Stack: 4 2 1
{[...] 0} {quackery 1} {[...] 11} {shell 5} {quackery 1} {[...] 1} {fib 15} {recurse 1} {fib 17} {recurse 1} {fib 1}
Stack: 4 1 2
{[...] 0} {quackery 1} {[...] 11} {shell 5} {quackery 1} {[...] 1} {fib 15} {recurse 1} {fib 17} {recurse 1} {fib 15} {recurse 1} {fib 1}
Stack: 4 1 1 0
{[...] 0} {quackery 1} {[...] 11} {shell 5} {quackery 1} {[...] 1} {fib 15} {recurse 1} {fib 17} {recurse 1} {fib 17} {recurse 1} {fib 1}
Stack: 4 1 0 1
{[...] 0} {quackery 1} {[...] 11} {shell 5} {quackery 1} {[...] 1} {fib 17} {recurse 1} {fib 1}
Stack: 2 4
{[...] 0} {quackery 1} {[...] 11} {shell 5} {quackery 1} {[...] 1} {fib 17} {recurse 1} {fib 15} {recurse 1} {fib 1}
Stack: 2 3 2
{[...] 0} {quackery 1} {[...] 11} {shell 5} {quackery 1} {[...] 1} {fib 17} {recurse 1} {fib 15} {recurse 1} {fib 15} {recurse 1} {fib 1}
Stack: 2 3 1 0
{[...] 0} {quackery 1} {[...] 11} {shell 5} {quackery 1} {[...] 1} {fib 17} {recurse 1} {fib 15} {recurse 1} {fib 17} {recurse 1} {fib 1}
Stack: 2 3 0 1
{[...] 0} {quackery 1} {[...] 11} {shell 5} {quackery 1} {[...] 1} {fib 17} {recurse 1} {fib 17} {recurse 1} {fib 1}
Stack: 2 1 3
{[...] 0} {quackery 1} {[...] 11} {shell 5} {quackery 1} {[...] 1} {fib 17} {recurse 1} {fib 17} {recurse 1} {fib 15} {recurse 1} {fib 1}
Stack: 2 1 2 1
{[...] 0} {quackery 1} {[...] 11} {shell 5} {quackery 1} {[...] 1} {fib 17} {recurse 1} {fib 17} {recurse 1} {fib 17} {recurse 1} {fib 1}
Stack: 2 1 1 2
{[...] 0} {quackery 1} {[...] 11} {shell 5} {quackery 1} {[...] 1} {fib 17} {recurse 1} {fib 17} {recurse 1} {fib 17} {recurse 1} {fib 15} {recurse 1} {fib 1}
Stack: 2 1 1 1 0
{[...] 0} {quackery 1} {[...] 11} {shell 5} {quackery 1} {[...] 1} {fib 17} {recurse 1} {fib 17} {recurse 1} {fib 17} {recurse 1} {fib 17} {recurse 1} {fib 1}
Stack: 2 1 1 0 1
5
Stack empty.
/O></pre>
=={{header|R}}==
<
{
bar <- function()
Line 486 ⟶ 1,947:
}
foo()</
<nowiki>[[1]]</nowiki>
foo()
Line 494 ⟶ 1,955:
You can also see the stack trace when a function is called (or as it exits) using the trace function.
<
foo()</
<pre>
Tracing foo() on entry
Line 505 ⟶ 1,966:
Selection:
</pre>
=={{header|Racket}}==
<syntaxhighlight lang="racket">
#lang racket
;; To see these calls we do two things: mutate the binding to prevent
;; Racket from inlining the value; use a (void) call at the end so the
;; calls are not tail calls (which will otherwise not show on the
;; stack).
(define foo #f)
(set! foo (λ() (bar) (void)))
(define bar #f)
(set! bar (λ() (show-stacktrace) (void)))
(define (show-stacktrace)
(for ([s (continuation-mark-set->context (current-continuation-marks))]
[i (in-naturals)])
;; show just the names, not the full source information
(when (car s) (printf "~s: ~s\n" i (car s)))))
(foo)
</syntaxhighlight>
Output:
<pre>
0: show-stacktrace
1: bar
2: foo
3: |[running body]|
</pre>
=={{header|Raku}}==
(formerly Perl 6)
{{works with|Rakudo|2013-03-03}}
<syntaxhighlight lang="raku" line>sub g { say Backtrace.new.concise }
sub f { g }
sub MAIN { f }</syntaxhighlight>
{{out}}
<pre> in sub g at bt:1
in sub f at bt:2
in sub MAIN at bt:3</pre>
=={{header|Raven}}==
<syntaxhighlight lang="raven"> [1 2 3 4] 42 { 'a' 1 'b' 2 'c' 3 } 34.1234 ( -1 -2 -3 ) "The quick brown fox" FILE dump</syntaxhighlight>
{{out}}
<pre>hash (4 items)
usage => 1
index => 65836
flags => 256
buffer => " 98252f8 73 74 64 69 6e 00 stdin."
The quick brown fox
28.1234
hash (3 items)
a => 1
b => 2
c => 3
42
list (4 items)
0 => 1
1 => 2
2 => 3
3 => 4</pre>
=={{header|REXX}}==
{{works with|Regina}}
<syntaxhighlight lang="rexx">/* call stack */
say 'Call A'
call A '123'
say result
exit 0
A:
say 'Call B'
call B '456'
say result
return ARG(1)
B:
say 'Call C'
call C '789'
say result
return ARG(1)
C:
call callstack
return ARG(1)
callstack: procedure
getcallstack(cs.)
say 'Dump call stack with' cs.0 'items'
do i = 1 to cs.0
parse var cs.i line func
say format(line, 3) ':' left(func, 9) ': source "' || sourceline(line) || '"'
end
return cs.0</syntaxhighlight>
{{out}}
<pre>prompt$ regina callstack.rexx
Call A
Call B
Call C
Dump call stack with 4 items
20 : CALLSTACK : source "call callstack"
15 : C : source "call C '789'"
9 : B : source "call B '456'"
3 : A : source "call A '123'"
789
456
123</pre>
Regina will also dump a call stack during certain error conditions. For instance, if the code listing above raised an unhandled signal (simulated here with "signal noname" in routine C). This is not a recoverable scenario though, and the program will not continue.
<syntaxhighlight lang="rexx">C:
signal noname
call callstack
return ARG(1)</syntaxhighlight>
{{out}}
<pre>prompt$ regina callstack.rexx
Call A
Call B
Call C
20 +++ signal noname
15 +++ call C '789'
9 +++ call B '456'
3 +++ call A '123'
Error 16 running "/demos/callstack.rexx", line 20: Label not found
Error 16.1: Label "NONAME" not found</pre>
=={{header|Ruby}}==
<
middle a+b, b+c
end
Line 520 ⟶ 2,108:
end
outer 2,3,5</
<pre>$ ruby stacktrace.rb
stacktrace.rb:10:in `inner'
Line 529 ⟶ 2,117:
Exceptions caught in a rescue clause contain the trace information:
<
middle a+b, b+c
end
Line 547 ⟶ 2,135:
puts e.backtrace
end
puts "continuing after the rescue..."</
<pre>stacktrace.rb:10:in `inner'
stacktrace.rb:6:in `middle'
Line 553 ⟶ 2,141:
stacktrace.rb:15
continuing after the rescue...</pre>
Thread has a backtrace method:
<syntaxhighlight lang="ruby">p Thread.current.backtrace</syntaxhighlight>
=={{header|Scala}}==
Line 558 ⟶ 2,148:
the way, could be used from Java as well, with minor modifications.
<
def printStackTrace = callStack drop 1 /* don't print ourselves! */ foreach println</
Usage example:
Line 613 ⟶ 2,203:
The following #printCurrentStack is already defined in the base slate image but it is replicated here.
<
[
d clone `>> [baseFramePointer: (d interpreter framePointerOf: #printCurrentStack).
Line 620 ⟶ 2,210:
].
Defining function 'printCurrentStack' on: 'Debugger traits'
[printCurrentStack &limit: &stream: &showLocation:]</
The output from calling the function:
<
Backtrace (method @ source):
frame: 0 [printCurrentStack &limit: &stream: &showLocation:] @ stdin:0
Line 637 ⟶ 2,227:
frame: 9 [start &resource:] @ src/lib/repl.slate:185
frame: 10 [start] @ src/mobius/prelude.slate:38
Nil</
=={{header|Smalltalk}}==
Line 644 ⟶ 2,234:
A backtrace is normally sent when some error occurs; however, it can be "forced":
<
Container class >> outer: a and: b and: c [
self middle: (a+b) and: (b+c)
Line 658 ⟶ 2,248:
Container outer: 2 and: 3 and: 5.
'Anyway, we continue with it' displayNl.</
Output:
Line 669 ⟶ 2,259:
=={{header|Tcl}}==
<
puts "Stack trace:"
for {set i 1} {$i < [info level]} {incr i} {
puts [string repeat " " $i][info level $i]
}
}</
Demonstration code:
<
middle [expr {$a+$b}] [expr {$b+$c}]
}
Line 685 ⟶ 2,275:
printStackTrace
}
outer 2 3 5</
Produces this output:
<pre>Stack trace:
Line 692 ⟶ 2,282:
inner 40</pre>
=={{header|VBA}}==
In VBE the VBA Editor hitting Control+L while stepping through your code in debug mode will pop up a window which displays the call stack.
=={{header|Wren}}==
You can always force Wren CLI to produce a stack trace by either engineering an actual error or calling Fiber.abort() at the relevant part of the script.
However, it is not possible to continue execution of the script afterwards. Whilst one can 'catch' such an error using Fiber.try() this will only allow you to inspect the error itself, not the chain of function calls that led up to it.
<syntaxhighlight lang="wren">var func2 = Fn.new {
Fiber.abort("Forced error.")
}
var func1 = Fn.new {
func2.call()
}
func1.call()</syntaxhighlight>
{{out}}
<pre>
Forced error.
[./stack_trace line 2] in new(_) block argument
[./stack_trace line 6] in new(_) block argument
[./stack_trace line 9] in (script)
</pre>
=={{header|zkl}}==
<syntaxhighlight lang="zkl">fcn f{println("F");vm.stackTrace().println()} fcn g{println("G")}
f();g();</syntaxhighlight>
{{out}}
stackTrace just returns a string. You don't get to futz with the stack.
<pre>
F
Stack trace for VM#1 ():
Cmd.f@stackTrace addr:4 args(0) reg(0)
Cmd.__constructor addr:3 args(0) reg(0) R
startup.__constructor addr:2242 args(0) reg(1) ER
startup.__constructor addr:2178 args(0) reg(22)
G
</pre>
{{omit from|AWK|No introspection}}
{{omit from|GUISS}}
{{omit from|Locomotive Basic|No introspection}}
{{omit from|Lotus 123 Macro Scripting|No introspection}}
{{omit from|PARI/GP}}
{{omit from|TI-83 BASIC}} {{omit from|TI-89 BASIC}}
{{omit from|M4}}
{{omit from|ZX Spectrum Basic|No introspection}}
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