From: Damphyr <damphyr@...>
Date: 2003-04-05T23:09:50+09:00
Subject: Re: Plugins (sort off)

Brian Candler wrote:
> On Sat, Apr 05, 2003 at 08:36:12PM +0900, Damphyr wrote:
> 
>>But then, how do we change the parameter to 
>>extend to be able to say something like
>>
>>module = myclass.very_clever_method_takes_string_returns_module(modulename)
>>a = Foo.new
>>a.extend module
> 
> 
> That should work just fine - you can pass modules around like any other
> object.
> 
> 
>>In essence what I want is to be able to evaluate a string and find out 
>>if it matches a symbol (or the texual representation of a symbol to be 
>>more accurate) in my class space, and then return that symbol or the 
>>object/class/module for that symbol
> 
> 
> symbols are global, so "symbol in my class space" doesn't quite make sense.
well a symbol I know that belongs (should belong? wants to belong? will 
belong? :) ) to my classes - I keep mixing words and definitions !very bad!.
> Do you mean "does object X have a method of name S"? There are a number of
> introspection techniques such as
>   self.class.instance_methods
>   self.singleton_methods
Actually what I mean is:

I have a file MyModule.rb with content:

Module MyModule
    def some_nice_method()
    end
end

and another file MyModule2.rb with content

Module MyModule2
    def some_nice_method()
    end
end

and somewhere else I have another script that should (or that I would 
like it to) be able to take in these files, and any later additions to 
that pre-specified "plugin repository" and do something like:

Class Experiment
    def doMethod(nameofmethod)
	self.extend nameofmethod
    end
end

the above does not execute (I know, I tried :)) ) and it would be silly 
if it did (I guess I'm a bit silly for trying :) ).
And that is what that

  very_clever_method_takes_string_returns_module(modulename)

should do. It's me as a programmer who knows that MyModule.rb has 
implicitly the same name as MyModule - now, how can I get the module by 
the string of it's name? (this sounds nice :) the string of it's name :) )
Probably impossible, (but I haven't looked in DBI or Freebase yet to see 
  how they do their plugins) so I went ahead and did module_eval on raw 
code. So yes, I'm essentially adding a new method to my class, not a 
module. What happens when I call module_eval again? From what I gather, 
the method gets overwritten.

OK, I have another description for my question:
I know beforehand that there is going to be a module, I have a way to 
determine the module's name as a string in runtime, I have a way to load 
that module into memory, but I have no way to call/extend/include the 
module because I don't know it's name (or I can't create a Module object 
from it's name).
Did I confuse everyone? I'll go away now and look some more...
:)
V.-


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