Devel::StackTrace(3) User Contributed Perl Documentation Devel::StackTrace(3)
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
" if $frame->hasargs;
}
# from bottom (least recent) of stack to top.
while (my $frame = $trace->prev_frame) {
print "Sub: ", $frame->subroutine, "
";
}
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
o Devel::StackTrace->new(%named_params)
Returns a new Devel::StackTrace object.
Takes the following parameters:
o frame_filter => $sub
By default, Devel::StackTrace will include all stack frames before the call to its 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.
o ignore_package => $package_name OR @package_names
Any frames where the package is one of these packages will not be on the stack.
o 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.
o 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.
o no_args => $boolean
If this parameter is true, then Devel::StackTrace will not store caller arguments in stack trace frames at all.
o 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.
o 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.
o 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.
o indent => $boolean
If this parameter is true, each stack frame after the first will start with a tab character, just like "Carp::confess()".
o $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.
o $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.
o $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.
o $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() ) );
o $trace->frame ($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.
o $trace->frame_count
Returns the number of frames in the trace object.
o $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)
perl v5.16.3 2012-11-20 Devel::StackTrace(3)