From: Geoff Stanley <geoffstanley@...>
Date: 2006-04-29T23:58:41+09:00
Subject: Re: Extending Methods

Thanks for all the responses!

Daniel Harple wrote:
> On Apr 27, 2006, at 3:26 AM, Geoff Stanley wrote:
> 
>> 1) The child classes wouldn't do
>> anything; They'd have to be hooked into the main program somehow...
>> troublesome and [...]
> 
> 1) Use Class#inherited

I was planning on using Class#inherited, but not for hooking each plugin 
in. I was going to use it solely to generate a list of plugins. Each 
plugin would be a .rb file that starts with a new class that inherits 
from GenericPlugin, and that class defines the plugin, giving it a name 
and description etc.

Sylvain Joyeux wrote:
> You can use Module and super
> 
> class Channel
> 	def initialize
> 		super if defined? super
> 	end
> end
> 
> module AChannelPlugin
> 	def initialize
> 		super if defined? super
> 		# Then write custom code. (To open a log file, for example.)
> 	end
> end
> 
> channel = Channel.new
> channel.extend AChannelPlugin # per-object plugin loading
> Channel.include AChannelPlugin # global plugin loading

This is a nice solution, except for this: Every method that is inherited 
(and those that aren't can do it too) has to have that 'super if 
defined? super' code in it. Perhaps that could be dynamically added to 
each method as it is created, I'm not sure.


I've thought some more about it, and came up with this solution of my 
own, that does in the end use super and inheritance.

    class Foo
        def testage
            puts "This is the base Foo class"
        end
    end

    class FooPlugin < Foo
        def testage
            super
            puts "Hello from the FooPlugin"
        end
    end
    Foo = FooPlugin

    class FooPlugin2 < Foo
        def testage
            super
            puts "Hello from FooPlugin2!"
        end
    end
    Foo = FooPlugin2

    Foo.new.testage

    # OUTPUT AS FOLLOWS:
    #test2.rb:13: warning: already initialized constant Foo
    #test2.rb:21: warning: already initialized constant Foo
    #This is the base Foo class
    #Hello from the FooPlugin
    #Hello from FooPlugin2!

The only problem is those warnings. Is there a different way of 
overwriting the Foo class with the FooPlugin class so that these 
warnings are not produced? I really don't want to have to resort to 
running my program with -W0 (warning level: silent).

Thanks once again!

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