From: Rick DeNatale <rick.denatale@...>
Date: 2007-03-31T08:23:39+09:00
Subject: Re: Find the fully qualified name of a class from a string

On 3/30/07, ara.t.howard@noaa.gov <ara.t.howard@noaa.gov> wrote:
> On Sat, 31 Mar 2007, Nasir Khan wrote:
>
> > Say you have a class definition in a string -
> >
> > str = <<EOF
> > module A
> >  class B
> >    def b
> >      puts "hello"
> >    end
> > end
> > end
> > EOF
> >
> > What is the easiest way to find out the fully qualified name of the class
> > there, namely "A::B"
> >
> > Now I could do a thing like
> >
> > module EmptyModule
> > end
> >
> > EmptyModule.module_eval(str)
> >
> > def self.find_class mod
> >   mod.constants.each do |str|
> >     m = mod.const_get(str)
> >       if m.class == Module
> >         find_class(m)
> >       else
> >         cname = m.to_s
> >         puts cname.match(/EmptyModule::/).post_match
> >         break
> >        end
> >      end
> >  end
> >
> > and call this method
> >
> > find_class(EmptyModule)
> >
> > which prints  "A::B"
> >
> > This works but it seems too much work to do something simple.
> >
> > Is there a better/simpler way to do this?
> >
> > Thanks
> > Nasir
>
> harp:~ > cat a.rb
> #
> # a better const_get
> #
>    def constant_get(hierachy)
>      ancestors = hierachy.split(%r/::/)
>      parent = Object
>      while((child = ancestors.shift))
>        klass = parent.const_get child
>        parent = klass
>      end
>      klass
>    end
>
>    c = constant_get 'A::B'

I don't think that's what he's looking for.

He has a string containing Ruby source code which presumably defines a
class (or classes?) which might be contained within a module. He
want's to find the fully qualified name of this unknown class (or
classes?).

 The A::B is really just an example.

WHY he wants to do this is beyond me.

-- 
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/