From: Trans <transfire@...>
Date: 2006-08-20T01:20:04+09:00
Subject: SOS Taskable

I'm stuck. I can't figure out how to implement Taskable. If you haven;t
seen my rantings abut this before, Taskable is an emulation of Rake's
task syntax:

  desc "this and that"

  task 'foo' => [ 'bar' ] do
     ...
  end

but limted to the scope of a module/class. Also, tasks themselves are
just be regular methods.

It's easy enough to define:

  class Module
    def task( name_preqs, &action )
      if Hash === name_preqs
        name = name_preqs.key
        preqs = name_preqs.value
      else
        name = name_preqs
        preqs = []
      end
      define_method( name ) do |*args|
         preqs.each {  |n| send(n,*args) }
         action.call(*args)
      end
    end
  end

The challenge comes from keeping track of the prequistes so they won't
get run more than once. With some help on this list I came to
understand that I needed to use TSort, that much seemed to work. But
problems arise in just looking up the tasks. Consider when a module
extends itself, then a task is called at the module level, how will it
look up a prerequiste that was defined at the instance level?

Anyway, the whole idea was to create a system that parallels Method,
UnboundMethod, instance_method, instance_methods, etc., but substitute
'task' for 'method'. Maybe this is just too low level to be pulled off
in pure Ruby? I'm on the verge of giving up --I'm weary of working on
it. Butmaybe someone else can see a clear soltuion?

Thanks,
T.