Devel::StackTrace(3) User Contributed Perl Documentation Devel::StackTrace(3)NAMEDevel::StackTrace - Stack trace and stack trace frame objects
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, 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()".
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
· 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 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.
· 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.
· 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.
· 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 it to truncate the argument's string representation
if it is longer than this number of characters.
· $trace->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 "next_frame" or "prev_frame"
will work properly.
· $trace->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 "next_frame" or "prev_frame"
will work properly.
· $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.
· $trace->frames
Returns a list of Devel::StackTraceFrame objects. The order they
are returned is from top (most recent) to bottom.
· $trace->frame ($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.
· $trace->frame_count
Returns the number of frames in the trace object.
· $trace->as_string
Calls as_string on each frame from top to bottom, producing output
quite similar to the Carp module's cluck/confess methods.
Devel::StackTraceFrame METHODS
See the caller documentation for more information on what these methods
return.
· $frame->package
· $frame->filename
· $frame->line
· $frame->subroutine
· $frame->hasargs
· $frame->wantarray
· $frame->evaltext
Returns undef if the frame was not part of an eval.
· $frame->is_require
Returns undef if the frame was not part of a require.
· $frame->args
Returns the arguments passed to the frame. Note that any arguments
that are references are returned as references, not copies.
· $frame->hints
· $frame->bitmask
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
Copyright (c) 2000-2006 David Rolsky. All rights reserved. This
program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
The full text of the license can be found in the LICENSE file included
with this module.
perl v5.10.1 2009-07-15 Devel::StackTrace(3)
