Devel::StackTrace(3pm)         User Contributed Perl Documentation         Devel::StackTrace(3pm)



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

VERSION
       version 1.34

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 AT rt.org.

AUTHOR
       Dave Rolsky <autarch AT 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)



perl v5.18.2                                2014-06-26                     Devel::StackTrace(3pm)