Caching of Subroutines

Łokě has asked for the wisdom of the Perl Monks concerning the following question:

Ok, now this baffles me to the core. I'm very simply using a subroutine:

sub reload_module {
    undefSub("on_public");

    delete $INC{"contrib.pl"};
    require "contrib.pl";
}
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to reload a module when using POE::Component::IRC. The on_public subroutine is the only sub (the only anything now) in the module contrib.pl (for testing). When I run the reloader, nothing reloads. However, here's when it gets funny. If I just write a testing script that does the same reload but not using POE, it works. Now, here are the two places I THINK there could be a problem. 1:

POE::Session->new
    ( _start => \&bot_start,
        irc_001    => \&on_connect,
        irc_public => \&on_public,
        irc_notice => \&on_notice,
        irc_msg    => \&on_msg,
    );
[download]

Could it be that when you use this type of session that it caches the subroutine? If so, how to I force this session to refresh without reconnecting? 2: In the on_public subroutine, it basically just outputs this

$_[KERNEL]->post( $irc{server} => privmsg => $irc{chan}, "\0037 this i
+s the standard test!");
[download]

Could it be caching that?? Anyone know? I'd bet it's #1 but I don't know how to go about clearing out that session info.

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Re: Caching of Subroutines by revdiablo (Prior) on Jan 03, 2005 at 18:30 UTC
Could it be that when you use this type of session that it caches the subroutine? No, that merely creates references to the subroutines. ~~You can update the subroutine at runtime, and as long as the reference points to the right thing, it will be fine.~~ [If there's a way to do this, I don't know it. Everything I've tried creates a new coderef, which means any old references point to the old sub.] Your problem is that when you undefine the sub, you are breaking the reference you previously created. A workaround to this could be: `POE::Session->new ( _start => \&bot_start, irc_001 => \&on_connect, irc_public => sub { on_public(@_) }, irc_notice => \&on_notice, irc_msg => \&on_msg, );` [download] Update: fixed a few errors. Another update: simonm's method may be preferable, as it uses the `&subroutine` calling variety to pass @_ implicitly. Another way would be `goto &subroutine` which replaces the current entry in the call stack.	[reply] [d/l] [select]
Re^2: Caching of Subroutines by Łokě (Scribe) on Jan 03, 2005 at 18:45 UTC
Nice solution. Can't use my globals anymore obviously but that can be worked around.	[reply]
Re: Caching of Subroutines by simonm (Vicar) on Jan 03, 2005 at 18:43 UTC
The `irc_public => \&on_public` reference continues to point to the original subroutine even after the package that contained it is reloaded. (This is what lets you wrap subroutines by saying `my $old = \&subname; *subname = sub { &$old }`.) As revdiablo suggests, pass a code reference that explicitly calls the subroutine by name so that the new definition will be found: `irc_public => sub { &MyPackage::subname }`.	[reply] [d/l] [select]