From: "Ara.T.Howard" <Ara.T.Howard@...>
Date: 2005-10-25T06:03:39+09:00
Subject: Re: A comparison by example of keyword argument styles

On Tue, 25 Oct 2005, Louis J Scoras wrote:

> Right, so this is probably a really dumb idea, but I was just having a
> little bit of fun. It would be cool if you could define methods like this:
>
> define :foo do
> required :bar, :baz
> optional :request => 'useless'
> named :side,
> :meat => 'fish'
> body do
> puts "Good, I got to say #{foo}#{bar}."
> puts "You thought of my third request was #{request}"
> puts "For dinner we have #{meat}"
> if side
> puts "With a side of #{side}"
> end
> end
> end
>
> foo 'hello ', 'world', :meat => 'steak', :side => 'potatoes'
>
> That is the first few times you wrote a definition like that. Then it would
> get very old very quickly I'm assuming ;)


   harp:~ > cat a.rb
   require 'parseargs'
   include ParseArgs

   def meth *argv
     pa =
       parseargs(argv) do
         req_arg 'foo', 'bar'
         opt_arg 'request' => 'useless'
         opt_kw 'side'
         opt_kw 'meat' => 'fish'
       end

     puts <<-txt
       Good, I got to say #{ pa.foo } #{ pa.bar }.
       You thought of my third request was #{ pa.request }
       For dinner we have #{ pa.meat }
     txt

     if pa.side
       puts "With a side of #{ pa.side }"
     end
   end

   meth 'hello ', 'world', 'useless', :meat => 'steak', :side => 'potatoes'

   harp:~ > ruby a.rb
       Good, I got to say hello  world.
       You thought of my third request was useless
       For dinner we have steak
   With a side of potatoes


note.  it's impossible to determine, if an argument is optional (your 'request'
above) if the last hash passed __is__ that optional argument itself or if it's
the set of keywords.  therfore you must pass 'useless' for the request in this
case - if you think about it the parsing is otheriwse impossible.

cheers.

-a
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