From: Robert Klemme <bob.news@...>
Date: 2004-08-09T22:21:17+09:00
Subject: Re: dynamic calling question


"Martin Pirker" <crf@sbox.tu-graz.ac.at> schrieb im Newsbeitrag
news:41176b8e$0$18044$3b214f66@aconews.univie.ac.at...
> On implementing a state machine I'm stuck at...
>
>
> h = Hash::new
> h["func1"] = "Outer::Inner::dothis"
> h["func2"] = "whatever"
>
> def whatever(x)
>  puts "whatever happens #{x}"
> end
>
> module Outer
>   module Inner
>     def dothis(c)
>       puts "I did it #{c} times"
>     end
>     module_function :dothis
>   end
> end
>
> Outer::Inner::dothis(3)
> __send__(h["func2"],9)
> __send__(h["func1"],7)
>
> === cut here ===
>
> $ ruby ztrick.rb
>
> I did it 3 times
> whatever happens 9
> ztrick.rb:21:in '__send__': undefined method 'Outer::Inner::dothis' for
main:Object (NoMethodError)
>         from ztest.rb:21
>
>
>
> local calls look ok - how to do dynamic calls across module/class
boundaries?
> consider the hash mostly populated first and the functions are defined
later
> (or never at all)
> I'm not even sure whether this is a syntax or missunderstanding issue
:-/

Misunderstanding I guess: __send__ without an instance sends to self,
which in this case != Outer::Inner.  So for the general case you need also
need the instance that the message should be sent to.  Try this:

h = Hash::new
h["func1"] = Outer::Inner.method :dothis
h["func2"] = method :whatever

def whatever(x)
 puts "whatever happens #{x}"
end

module Outer
  module Inner
    def dothis(c)
      puts "I did it #{c} times"
    end
    module_function :dothis
  end
end

Outer::Inner::dothis(3)
h["func2"].call 9
h["func1"].call 7

Regards

    robert