Re: Thorny design problem

I don't see any particular reason to use eval. Why not do something like this?

sub do_em {
    ...
    my $module = 'Crunch::' . $company;
    require $module; 
    $module->do_it( $dir );
  }
}
[download]

Update: Actually that should be:

    my $module = 'Crunch/' . $company . '.pm';
[download]

...per mpeters' note below.

There are also some CPAN modules for doing plugins which will scan a directory and load each module fitting some criteria, so you don't even have to do the require.

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Re^2: Thorny design problem by mpeters (Chaplain) on Sep 07, 2005 at 21:40 UTC
No, this won't actually work. From perldoc: But if you try this: `$class = ’Foo::Bar’; require $class; # $class is not a bareword #or require "Foo::Bar"; # not a bareword because of the ""` [download] The require function will look for the "Foo::Bar" file in the @INC array and will complain about not finding "Foo::Bar" there. In this case you can do: `eval "require $class";` [download] But you could do: `my $module = 'Crunch/' . $company .'.pm'; require $module;` [download] -- More people are killed every year by pigs than by sharks, which shows you how good we are at evaluating risk. -- Bruce Schneier	[reply] [d/l] [select]
Re^2: Thorny design problem by tlm (Prior) on Sep 07, 2005 at 21:36 UTC
Thanks for the cluebrick~~s on `eval`, and~~ on the keyword "plugin", which hadn't occurred to me. Searching for "plugin" in CPAN brings down about 600 hits, most of which are not general enough (e.g. `Siesta::Plugin, PXP::Plugin`, etc.), so I have some wading to do. If you remember any specific names, please let know. Update: Thanks to mpeters for reminding me why I was fussing with `eval`. the lowliest monk	[reply]
Re^3: Thorny design problem by mpeters (Chaplain) on Sep 07, 2005 at 21:42 UTC
It's actually not so much a 'plugin' architecture, but a 'factory' design patter. Check out Class::Factory. -- More people are killed every year by pigs than by sharks, which shows you how good we are at evaluating risk. -- Bruce Schneier	[reply]