From: Ronald Fischer <ronald.fischer@...>
Date: 2007-08-31T17:18:08+09:00
Subject: Dispatching when function name is stated as a symbol

Can someone point out an elegant way to solve the following problem?

I have a module with a function f and additional functions g1, g2, ..., 
which basically looks like this:

module M
  def f(&cb)
    ...
    x=cb.call
    # DO SOMETHING .... see below
  end
  def g1(a,b,c)
    ...
  end
  def g2(d,e)
    ...
  end
  # etc
end

The DO SOMETHING part looks like this: The proc object being called 
is supposed to return an array, where the first element is a symbol
corresponding to one of the function names g1, g2 ...., and the 
remaining array elements corresponding to the parameters of this
function. Hence, if 
  x=cb.call
causes x to contain [:g2, 25, 'dummy'], I would like to execute
  g2(25,'dummy')

I have not found a convincing way of doing this. Of course I can
use a big case ... end on the function names (ugly). I can turn
the symbol :g2 into a string 'g2', marshal the arguments and put
together a string containing the function call (even uglier).
I also thought about using a hash of proc object (the keys being
the symbols, the values being the procedures), kind of

  {:g1 => proc {|a,b,c] g1(a,b,c)}, :g2 => proc {|d,e| g2(d,e)
},...}[x[0]].
  call(*x[1..-1])

but this looks like tremendous overkill too. Is there a simpler
way of doing it?

Ronald
-- 
Ronald Fischer <ronald.fischer@venyon.com>
Phone: +49-89-452133-162

-- 
Ronald Fischer <ronald.fischer@venyon.com>
Phone: +49-89-452133-162