Devel::StackTrace - Stack trace and stack trace frame objects

  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 $f->hasargs;
  }

  # from bottom (least recent) of stack to top.
  while (my $frame = $trace->prev_frame)
  {
      print "Sub: ", $f->subroutine, "\n";
  }

The Devel::StackTrace module contains two classes, Devel::StackTrace and Devel::StackTraceFrame. 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::StackTraceFrame objects, one for each level of the stack. The frames contain all the data available from caller() as of Perl 5.6.0 though this module still works with 5.00503.

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

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.
  }

* new(%named_params)

Returns a new Devel::StackTrace object. Takes the following parameters: Any frames where the package is one of these packages will not be on the stack. Any frames where the package is a subclass of one of these packages (or is the same package) will not be on the stack. Devel::StackTrace internally adds itself to the 'ignore_package' parameter, meaning that the Devel::StackTrace package is ALWAYS ignored. However, if you create a subclass of Devel::StackTrace it will not be ignored. If this parameter is true, then Devel::StackTrace will not store references internally when generating stacktrace frames. This lets your objects go out of scope. Devel::StackTrace replaces any references with their stringified representation. By default, Devel::StackTrace will call CWoverload::StrVal() to get the underlying string representation of an object, instead of respecting the object's stringification overloading. If you would prefer to see the overloaded representation of objects in stack traces, then set this parameter to true.

* next_frame

Returns the next Devel::StackTraceFrame 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 CWnext_frame or CWprev_frame will work properly.

* prev_frame

Returns the next Devel::StackTraceFrame 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 CWnext_frame or CWprev_frame will work properly.

* reset_pointer

Resets the pointer so that the next call CWnext_frame or CWprev_frame will start at the top or bottom of the stack, as appropriate.

* frames

Returns a list of Devel::StackTraceFrame objects. The order they are returned is from top (most recent) to bottom.

* 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.

* frame_count

Returns the number of frames in the trace object.

* as_string

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

See the caller documentation for more information on what these methods return.

* package

* filename

* line

* subroutine

* hasargs

* wantarray

* evaltext

Returns undef if the frame was not part of an eval.

* is_require

Returns undef if the frame was not part of a require.

* args

Returns the arguments passed to the frame. Note that any arguments that are references are returned as references, not copies.

* hints

* bitmask

Dave Rolsky, <autarch@urth.org>

Exception::Class