Use the Carp module to show you the stack trace, i.e. each sub routine call in the source code from which you started the program to where you are printing the debug output. Carp comes with Perl.
use Carp qw/ cluck confess longmess /;
# die of errors with stack backtrace
confess("title: ($title)")
# warn of errors with stack backtrace
cluck("Before escaping title ($title)");
$title = $self->escape($title);
cluck("After escaping title ($title)");
# longmess - return the message that cluck and confess produce
$self->log_error( "title not set: " . longmess() );
Carp on search.cpan.org appears to identify perl itself and doesn't provide POD for some reason, but see: perldoc Carp.
Another useful module is Carp::Always, which makes all dies and warns emit stack traces.
Note that this will change exception strings, so any eval BLOCK that checks for specific exception matches against $@ may fail because of this.
Enable Carp::Always with a regular "use" statement in the code, or temporarily from the command line using one of these:
perl -MCarp::Always your_program.pl
#or, depending on the shell/CMD
export PERL5OPT=-MCarp::Always
set PERL5OPT=-MCarp::Always
Or from within Emacs using the M-x setenv function. This is useful if you run Perl programs using the *compilation* mode.
/J
-
Are you posting in the right place? Check out Where do I post X? to know for sure.
-
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
-
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
-
Want more info? How to link
or How to display code and escape characters
are good places to start.