NAME

Devel::StackTrace - An object representing a stack trace

VERSION

version 2.01

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, C,Devel::StackTrace> and Devel::StackTrace::Frame. These objects encapsulate the information that can retrieved via Perl's 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.
  }

METHODS

This class provide the following 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 on the stack, going down. If this method 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 $trace->next_frame() or $trace->prev_frame() will work properly.

$trace->prev_frame()

Returns the next Devel::StackTrace::Frame object on the stack, going up. If this method 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 the next call to $trace->next_frame() or $trace->prev_frame() will work properly.

$trace->reset_pointer

Resets the pointer so that the next call to $trace->next_frame() or $trace->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.

This is useful if you want to filter the list of frames in ways that are more complex than can be handled by the $trace->filter_frames() method:

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

$trace->frame($index)

Given an index, this method returns the relevant frame, or undef if there is no 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 $frame->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 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>

CONTRIBUTORS

COPYRIGHT AND LICENSE

This software is Copyright (c) 2000 - 2016 by David Rolsky.

This is free software, licensed under:

  The Artistic License 2.0 (GPL Compatible)