Once upon a time I wrote a C++ MP3 streaming server, this had a core of code, and a framework for plugins.

 These plugins worked pretty simply via 'dlopen', etc.

 Now I'm recoding the server in perl, and I'd like to have a simple means of extending the software.

 Initially I though I could have a 'Plugins::Foo' package and 'use/require' it at runtime via 'eval' however this has the problem that the package loaded thusly can't access variables in the main scope of the server, because they're defined via 'my $foo = ..'.

 Is there a simple solution to this, without using 'our'??

 Right now the best solution I've got is something along these lines: (This loads the code via an eval; with the sideeffect that the three plugin functions are present at ::main:: scope - and can access things)

    $plugin = 'foo';

    if ( -e $plugin . ".pm" )
    {
       #load plugin, import it into main scope.
       my $fileContents = &readFile( $plugin . ".pm" );
       eval( $fileContents );
       if ( $@ )  { handlePluginLoadError($@); exit; }
  
       # The following three functions _MUST_ be defined
       # by the plugin which has been loaded.  Could test
       # they are present via symbol table introspection 
       # to be sure, I guess.
       &pluginInit( "foo" );
       &pluginProcess( "bar" );
       &pluginTerminae( "baz" );

       # Unload those functions so that they may be
       # reloaded without duplication warnings
       undef( &pluginInit );
       undef( &pluginProcess );
       undef( &pluginTerminate );
    }

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In reply to Coding perl a plugin system? by skx

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