NAME
    Devel::StackTrace - An object representing a stack trace

VERSION
    version 1.33

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:

    *   frame_filter => $sub

        By default, Devel::StackTrace will include all stack frames before
        the call to its constructor.

        However, you may want to filter out some frames with more
        granularity than 'ignore_package' or 'ignore_class' allow.

        You can provide a subroutine which is called with the raw frame data
        for each frame. This is a hash reference with two keys, "caller",
        and "args", both of which are array references. The "caller" key is
        the raw data as returned by Perl's "caller()" function, and the
        "args" key are the subroutine arguments found in @DB::args.

        The filter should return true if the frame should be included, or
        false if it should be skipped.

    *   filter_frames_early => $boolean

        If this parameter is true, "frame_filter" will be called as soon as
        the stacktrace is created, and before refs are stringified (if
        "no_refs" is true), rather than being filtered lazily when
        Devel::StackTrace::Frame objects are first needed.

        This is useful if you want to filter based on the frame's arguments
        and want to be able to examine object properties, for example.

    *   ignore_package => $package_name OR \@package_names

        Any frames where the package is one of these packages will not be on
        the stack.

    *   ignore_class => $package_name OR \@package_names

        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.

    *   skip_frames => $integer

        This will cause this number of stack frames to be excluded from top
        of the stack trace. This prevents the frames from being captured at
        all, and applies before the "frame_filter", "ignore_package", or
        "ignore_class" options, even with "filter_frames_early".

    *   no_refs => $boolean

        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.

    *   no_args => $boolean

        If this parameter is true, then Devel::StackTrace will not store
        caller arguments in stack trace frames at all.

    *   respect_overload => $boolean

        By default, Devel::StackTrace will call "overload::AddrRef()" 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.

    *   max_arg_length => $integer

        By default, Devel::StackTrace will display the entire argument for
        each subroutine call. Setting this parameter causes truncates each
        subroutine argument's string representation if it is longer than
        this number of characters.

    *   message => $string

        By default, Devel::StackTrace will use 'Trace begun' as the message
        for the first stack frame when you call "as_string". You can supply
        an alternative message using this option.

    *   indent => $boolean

        If this parameter is true, each stack frame after the first will
        start with a tab character, just like "Carp::confess()".

  $trace->next_frame()
    Returns the next Devel::StackTrace::Frame object on the stack, going
    down. If this method hasn't been called before it returns the first
    frame. It returns "undef" when it reaches the bottom of the stack and
    then resets its pointer so the next call to "$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>

COPYRIGHT AND LICENSE
    This software is Copyright (c) 2014 by Dave Rolsky.

    This is free software, licensed under:

      The Artistic License 2.0 (GPL Compatible)

