1Devel::StackTrace(3) User Contributed Perl Documentation Devel::StackTrace(3)
2
6 Devel::StackTrace - An object representing a stack trace
7
9 version 1.27
10
12 use Devel::StackTrace;
13 my $trace = Devel::StackTrace->new;
15 print $trace->as_string; # like carp
17 # from top (most recent) of stack to bottom.
19 while (my $frame = $trace->next_frame) {
20 print "Has args\n" if $frame->hasargs;
21 }
22 # from bottom (least recent) of stack to top.
24 while (my $frame = $trace->prev_frame) {
25 print "Sub: ", $frame->subroutine, "\n";
26 }
27
29 The Devel::StackTrace module contains two classes, Devel::StackTrace
30 and Devel::StackTrace::Frame. The goal of this object is to
31 encapsulate the information that can found through using the caller()
32 function, as well as providing a simple interface to this data.
33 The Devel::StackTrace object contains a set of Devel::StackTrace::Frame
35 objects, one for each level of the stack. The frames contain all the
36 data available from "caller()".
37 This code was created to support my Exception::Class::Base class (part
39 of Exception::Class) but may be useful in other contexts.
40
42 When describing the methods of the trace object, I use the words 'top'
43 and 'bottom'. In this context, the 'top' frame on the stack is the
44 most recent frame and the 'bottom' is the least recent.
45 Here's an example:
47 foo(); # bottom frame is here
49 sub foo {
51 bar();
52 }
53 sub bar {
55 Devel::StackTrace->new; # top frame is here.
56 }
57
59 · Devel::StackTrace->new(%named_params)
60 Returns a new Devel::StackTrace object.
62 Takes the following parameters:
64 · frame_filter => $sub
66 By default, Devel::StackTrace will include all stack frames
68 before the call to its its constructor.
69 However, you may want to filter out some frames with more
71 granularity than 'ignore_package' or 'ignore_class' allow.
72 You can provide a subroutine which is called with the raw
74 frame data for each frame. This is a hash reference with
75 two keys, "caller", and "args", both of which are array
76 references. The "caller" key is the raw data as returned by
77 Perl's "caller()" function, and the "args" key are the
78 subroutine arguments found in @DB::args.
79 The filter should return true if the frame should be
81 included, or false if it should be skipped.
82 · ignore_package => $package_name OR \@package_names
84 Any frames where the package is one of these packages will
86 not be on the stack.
87 · ignore_class => $package_name OR \@package_names
89 Any frames where the package is a subclass of one of these
91 packages (or is the same package) will not be on the stack.
92 Devel::StackTrace internally adds itself to the
94 'ignore_package' parameter, meaning that the
95 Devel::StackTrace package is ALWAYS ignored. However, if
96 you create a subclass of Devel::StackTrace it will not be
97 ignored.
98 · no_refs => $boolean
100 If this parameter is true, then Devel::StackTrace will not
102 store references internally when generating stacktrace
103 frames. This lets your objects go out of scope.
104 Devel::StackTrace replaces any references with their
106 stringified representation.
107 · respect_overload => $boolean
109 By default, Devel::StackTrace will call
111 "overload::AddrRef()" to get the underlying string
112 representation of an object, instead of respecting the
113 object's stringification overloading. If you would prefer
114 to see the overloaded representation of objects in stack
115 traces, then set this parameter to true.
116 · max_arg_length => $integer
118 By default, Devel::StackTrace will display the entire
120 argument for each subroutine call. Setting this parameter
121 causes it to truncate the argument's string representation
122 if it is longer than this number of characters.
123 · message => $string
125 By default, Devel::StackTrace will use 'Trace begun' as the
127 message for the first stack frame when you call
128 "as_string". You can supply an alternative message using
129 this option.
130 · indent => $boolean
132 If this parameter is true, each stack frame after the first
134 will start with a tab character, just like
135 "Carp::confess()".
136 · $trace->next_frame
138 Returns the next Devel::StackTrace::Frame object down on the stack.
140 If it hasn't been called before it returns the first frame. It
141 returns undef when it reaches the bottom of the stack and then
142 resets its pointer so the next call to "next_frame" or "prev_frame"
143 will work properly.
144 · $trace->prev_frame
146 Returns the next Devel::StackTrace::Frame object up on the stack.
148 If it hasn't been called before it returns the last frame. It
149 returns undef when it reaches the top of the stack and then resets
150 its pointer so pointer so the next call to "next_frame" or
151 "prev_frame" will work properly.
152 · $trace->reset_pointer
154 Resets the pointer so that the next call "next_frame" or
156 "prev_frame" will start at the top or bottom of the stack, as
157 appropriate.
158 · $trace->frames
160 Returns a list of Devel::StackTrace::Frame objects. The order they
162 are returned is from top (most recent) to bottom.
163 · $trace->frame ($index)
165 Given an index, returns the relevant frame or undef if there is not
167 frame at that index. The index is exactly like a Perl array. The
168 first frame is 0 and negative indexes are allowed.
169 · $trace->frame_count
171 Returns the number of frames in the trace object.
173 · $trace->as_string
175 Calls as_string on each frame from top to bottom, producing output
177 quite similar to the Carp module's cluck/confess methods.
178
180 Please submit bugs to the CPAN RT system at
181 http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Devel%3A%3AStackTrace or
182 via email at bug-devel-stacktrace@rt.cpan.org.
183
185 Dave Rolsky <autarch@urth.org>
186
188 This software is Copyright (c) 2011 by Dave Rolsky.
189 This is free software, licensed under:
191 The Artistic License 2.0 (GPL Compatible)
193perl v5.12.3 2011-01-16 Devel::StackTrace(3)