Hook::Filter 0.02

Hook::Filter is a runtime filtering layer on top of subroutine calls.

SYNOPSIS

Imagine you have a big program using a logging library that exports 3 functions called mydebug, myinfo and mywarn. Those functions generate far too much log, so you want to skip calling them except in some specific circumstances.

In your main program, write:

use Hook::Filter hook => ["mydebug","myinfo","mywarn"];

In all modules making use of the logging library, write:

use Hook::Filter;

Then create a file called ./hook_filter.rules. This file contains boolean expressions that specify when calls to the filtered subroutines should be allowed:

# allow calls to mydebug only inside package My::Filthy:Attempt
is_sub(mydebug) && from_pkg(My::Filthy::Attempt)

# allow all calls to myinfo except from inside packages under the namespace My::Test::
is_sub(myinfo) && !from_pkg(/^My::Test/)

# allow calls to mywarn from function do_stuff in package main
# whose third argument is a message that does not match the string invalid login name
is_sub(mywarn) && from_sub(do_stuff) && from_pkg(main) && !has_arg(3,/invalid login name/)

# all other calls to myinfo, mydebug or mywarn will be skipped

SYNOPSIS, Log::Dispatch

Your program uses Log::Dispatch. You want to enable Hook::Filter on top of the methods log and log_to from Log::Dispatch everywhere at once. And you want to use the filter rules located in /etc/myconf/filter_rules.conf. Easy: in main, write:

use Hook::Filter rules => /etc/myconf/filter_rules.conf, hook => [Log::Dispatch::log,Log::Dispatch::log_to];