From: ara.t.howard@...
Date: 2007-01-03T04:51:15+09:00
Subject: Re: Detecting default used in method calls

On Wed, 3 Jan 2007, Peter Lynch wrote:

> I would like to know if a function has been called with or without an
> optional argument.
>
> If I have -
>
> def the_Function (a, b = '')
> end
>
> and I invoke it like this -
>
> the_Function('a')
> the_Function('a', '')
>
> is there any way for me to tell within the_Function which form of
> invocation was used?

   def the_function *a, &b
     case a.size
       when 0
         p 'zero args'
       when 1
         p 'one arg'
       when 2
         p 'two args'
       else
         raise ArgumentError
     end

     # ...
   end


but methods like this are often confusing to read

   the_function 'arg'

   the_function 'arg', 'wtf does this do?'

it's often better and more rubyish to use options

   def the_function arg, opts = {}, &block
     b = opts['b'] || opts[:b]
     # ....
   end


regards.


-a
-- 
if you find yourself slandering anybody, first imagine that your mouth is
filled with excrement.  it will break you of the habit quickly enough. - the
dalai lama