NAME¶

Devel::StackTrace - An object representing a stack trace

VERSION¶

version 1.30

SYNOPSIS¶

  use Devel::StackTrace;
  my $trace = Devel::StackTrace->new;
  print $trace->as_string; # like carp
  # from top (most recent) of stack to bottom.
  while (my $frame = $trace->next_frame) {
      print "Has args\n" if $frame->hasargs;
  }
  # from bottom (least recent) of stack to top.
  while (my $frame = $trace->prev_frame) {
      print "Sub: ", $frame->subroutine, "\n";
  }

DESCRIPTION¶

The Devel::StackTrace module contains two classes, Devel::StackTrace and Devel::StackTrace::Frame. The goal of this object is to encapsulate the information that can found through using the caller() function, as well as providing a simple interface to this data.

The Devel::StackTrace object contains a set of Devel::StackTrace::Frame objects, one for each level of the stack. The frames contain all the data available from "caller()".

This code was created to support my Exception::Class::Base class (part of Exception::Class) but may be useful in other contexts.

'TOP' AND 'BOTTOM' OF THE STACK¶

When describing the methods of the trace object, I use the words 'top' and 'bottom'. In this context, the 'top' frame on the stack is the most recent frame and the 'bottom' is the least recent.

Here's an example:

  foo();  # bottom frame is here
  sub foo {
     bar();
  }
  sub bar {
     Devel::StackTrace->new;  # top frame is here.
  }

Devel::StackTrace METHODS¶

•

Devel::StackTrace->new(%named_params)

Returns a new Devel::StackTrace object.

Takes the following parameters:

• $trace->next_frame

  Returns the next Devel::StackTrace::Frame object down on the stack. If it hasn't been called before it returns the first frame. It returns undef when it reaches the bottom of the stack and then resets its pointer so the next call to "next_frame" or "prev_frame" will work properly.

• $trace->prev_frame

  Returns the next Devel::StackTrace::Frame object up on the stack. If it hasn't been called before it returns the last frame. It returns undef when it reaches the top of the stack and then resets its pointer so pointer so the next call to "next_frame" or "prev_frame" will work properly.

• $trace->reset_pointer

  Resets the pointer so that the next call "next_frame" or "prev_frame" will start at the top or bottom of the stack, as appropriate.

• $trace->frames

  When this method is called with no arguments, it returns a list of Devel::StackTrace::Frame objects. They are returned in order from top (most recent) to bottom.

  This method can also be used to set the object's frames if you pass it a list of Devel::StackTrace::Frame objects objects.

  This is useful if you want to filter the list of frames in ways that are more complex than can be handled by "filter_frames":

    $stacktrace->frames( my_filter( $stacktrace->frames() ) );
      

• $trace->frame ($index)

  Given an index, returns the relevant frame or undef if there is not frame at that index. The index is exactly like a Perl array. The first frame is 0 and negative indexes are allowed.

• $trace->frame_count

  Returns the number of frames in the trace object.

• $trace->as_string(\%p)

  Calls as_string on each frame from top to bottom, producing output quite similar to the Carp module's cluck/confess methods.

  The optional "\%p" parameter only has one useful option. The "max_arg_length" parameter truncates each subroutine argument's string representation if it is longer than this number of characters.

SUPPORT¶

Please submit bugs to the CPAN RT system at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Devel%3A%3AStackTrace or via email at bug-devel-stacktrace@rt.cpan.org.

AUTHOR¶

Dave Rolsky <autarch@urth.org>

COPYRIGHT AND LICENSE¶

This software is Copyright (c) 2012 by Dave Rolsky.

This is free software, licensed under:

  The Artistic License 2.0 (GPL Compatible)