NAME
Devel::StackTrace - An object representing a stack trace
VERSION
version 1.31
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.
* 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.
* 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)