Perl – How to get a call stack listing in Perl

callstackperlstack-trace

Is there a way I can access (for printout) a list of sub + module to arbitrary depth of sub-calls preceding a current position in a Perl script?

I need to make changes to some Perl modules (.pm's). The workflow is initiated from a web-page thru a cgi-script, passing input through several modules/objects ending in the module where I need to use the data. Somewhere along the line the data got changed and I need to find out where.

Best Answer

You can use Devel::StackTrace.

use Devel::StackTrace;
my $trace = Devel::StackTrace->new;
print $trace->as_string; # like carp

It behaves like Carp's trace, but you can get more control over the frames.

The one problem is that references are stringified and if a referenced value changes, you won't see it. However, you could whip up some stuff with PadWalker to print out the full data (it would be huge, though).

Related Solutions

Javascript – How to get a JavaScript stack trace when I throw an exception

Edit 2 (2017):

In all modern browsers you can simply call: console.trace(); (MDN Reference)

Edit 1 (2013):

A better (and simpler) solution as pointed out in the comments on the original question is to use the stack property of an Error object like so:

function stackTrace() {
    var err = new Error();
    return err.stack;
}

This will generate output like this:

DBX.Utils.stackTrace@http://localhost:49573/assets/js/scripts.js:44
DBX.Console.Debug@http://localhost:49573/assets/js/scripts.js:9
.success@http://localhost:49573/:462
x.Callbacks/c@http://localhost:49573/assets/js/jquery-1.10.2.min.js:4
x.Callbacks/p.fireWith@http://localhost:49573/assets/js/jquery-1.10.2.min.js:4
k@http://localhost:49573/assets/js/jquery-1.10.2.min.js:6
.send/r@http://localhost:49573/assets/js/jquery-1.10.2.min.js:6

Giving the name of the calling function along with the URL, its calling function, and so on.

Original (2009):

A modified version of this snippet may somewhat help:

function stacktrace() { 
  function st2(f) {
    return !f ? [] : 
        st2(f.caller).concat([f.toString().split('(')[0].substring(9) + '(' + f.arguments.join(',') + ')']);
  }
  return st2(arguments.callee.caller);
}

Java – How to get the current stack trace in Java

You can use Thread.currentThread().getStackTrace().

That returns an array of StackTraceElements that represent the current stack trace of a program.

Best Answer

Related Solutions

Javascript – How to get a JavaScript stack trace when I throw an exception

Java – How to get the current stack trace in Java

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