callback::hook - unified hooks for system/module programming
in module code that uses a callback, just define subroutines that start "hook_"
package my_foo_module;
use callback::hook;
sub hook_after_foo{
print "foo phase is complete, after_foo hook got args: @_\n";
};
in system code that calls callbacks, find them in the callback::hook name space.
package mainfoo;
...
callback::hook::before_foo($this);
$this->do_the_foo;
callback::hook::after_foo($this);
Another in a continuing series of short, subtle CPAN modules, callback::hook provides a standard interface for writing routines that will get called at defined times in the processing internal to a system, and a standard way for calling the routines at those defined times.
Right before beginning run-time, all packages that use callback::hook are scanned for subroutines with names matching /hook_(.+)/ and any such subroutines are pushed onto @{"callback::hook::$1"} arrays.
When code calls callback::hook::NAME, all subroutines in @callback::hook::NAME are executed, in array context, and the results of each are stored in %callback::hook::results under the coderef as a key.
you can find out the result of the last call to your package's coderef on the NAME hook by looking at the @{$callback::hook::results{\&hook_NAME}} array.
None. This module imports coderefs from the callers space and lists them in arrays in its own space, rather than exporting anything.
Only one subroutine per callback-name per package. So if you need to create multiple callbacks on the same hook, either directly manipulate the @callback::hook::NAME array for your callback's name, or declare each callback function in its own package, that all use callback::hook.
Written after reading about automatic callback discovery on the qpsmtpd mailing list, in response to a request from Tim Bunce, for possible use with DBI.
please use rt.cpan.org for bug reports and feedback.
David Nicol <davidnico@cpan.org>
Copyright (C) 2005 by David Nicol
Released under GNU Public License version 2. The author does not believe that linking in a library for use constitutes creation of a derivative work.
