in reply to Defensive Programming and Audit Trails

Under mod_perl when working with external modules and most templating/frameworks I have found code similar to this helpful:
# OO method for error to STDERR uisng 'warn' # which under mod_perl/Apache is your # default error_log sub error_to_log { my ($self,$error,$override) = @_; if ($self->_debug() || $override) { warn "$error\n"; } }
So if your _debug method is toggled on this comment would get logged:
$object->error_to_log("I made it this far, I can't believe it");

If you don't "advertise"* the _debug method or you are doing a minor debug you could simply call it with:
$object->error_to_log("Date: $date Variable: $var",1);
The '1' simply forces the error message to be written.

There are many more robust solutions available, but I have found this method to be very useful and allows me control over the error logging process. Since it is abstracted(?) enough I can make changes to the logging method without recoding other sections of the application.

So you don't want OO?
# $debug is a global variable # you will need to assign sub error_to_log { my ($error,$override) = @_; if ($debug || $override) { warn "$error\n"; } }

Then you call it like any other sub:
&error_to_log("Error message");

* In Perl it is not as common to make a method completely private, as it may be in languages like Java. In most cases they are still acessible if you know they exist, that is why I prefer the "advertise" verbiage. Ways to make a method private can be found in other nodes, but I didn't bother to look them up because this node is about logging not private vs. public methods.