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Re: Reloading modules- suppressing warnings works sometimes?

by !1 (Hermit)
on Dec 21, 2003 at 01:27 UTC ( #316120=note: print w/replies, xml ) Need Help??


in reply to Reloading modules- suppressing warnings works sometimes?

Perhaps:

package reload; use strict; use warnings; sub reload { my ($PM) = @_ or return; $PM =~ s!::!/!g; $PM .= ".pm"; delete $INC{$PM}; no strict 'refs'; no warnings 'redefine'; my $warnings = \&warnings::import; local *warnings::import = sub { &{$warnings}; unimport warnings "redefine"; }; eval { require $PM }; } 1;

It should still work as before except it won't spew out redefine errors.

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Re: Re: Reloading modules- suppressing warnings works sometimes?
by JPaul (Hermit) on Dec 21, 2003 at 20:07 UTC
    Greetings;

    I have to admit - I don't fully understand entirely what the above does - I've only got a vague idea - but it works perfectly :)

    Well done :)

    JP,
    -- Alexander Widdlemouse undid his bellybutton and his bum dropped off --

      In a nutshell:

      sub reload { my ($PM) = @_ or return; $PM =~ s!::!/!g; $PM .= ".pm"; delete $INC{$PM};

      We return unless we get something to load. After that, we convert all ::'s to / and append .pm to the end of our module name because that's how it's stored in %INC and it keeps us from needing to eval string.

      no strict 'refs'; no warnings 'redefine';

      Just what it says.

      my $warnings = \&warnings::import; local *warnings::import = sub { &{$warnings}; unimport warnings "redefine"; };

      Ok. The magic happens here. $warnings contains a coderef to the warnings import method. It's very important that we keep this since warnings.pm may change between versions and we'd very much enjoy this not breaking just because we have a new warnings module. Anywho, the next line localizes the warnings::import typeglob. To this, we assign a subroutine that first calls our old warnings::import method with all the same parameters. Notice that I call it as &{$warnings} instead of $warnings->(). I could have done $warnings->(@_) as well, but what fun is that? Anyhow, since we imported whatever the calling script/module wanted we need to unimport the redefine warning immediately afterwards. Remember that this gets called from the module in question whenever it uses warnings. Thus it will affect the $^WARNING_BITS variable at that point.

      eval { require $PM }; }

      I love eval braces. Of course, it's used here because if require can't find the module it will kill the script. Just check the return from reload::reload to make certain the module did in fact load. Also of note is that at the end of the subroutine, warnings::import is magically restored to its old import method.

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