From: zdennis <zdennis@...>
Date: 2005-11-05T11:31:09+09:00
Subject: Re: Optional block arguments?

Vincent Foley wrote:
> How can I have a block that optionally takes an argument?  Thanks.

This has been involved in a recent discussion for how-to handle true anonymous functions in ruby. 
Currently you can't do this with proc or Procs, the same way you can with methods. A workaround is 
to use *args, since it will capture any/all parameters passed to the method and put them in an array:

irb(main):013:0> pr = proc { |*args| args.length }
=> #<Proc:0xb7c8f154@(irb):13>
irb(main):014:0> pr.call
=> 0
irb(main):015:0> pr.call "hey"
=> 1
irb(main):016:0> pr.call [ 1,2,3 ]
=> 1
irb(main):017:0> pr.call [ 1,2,3 ], :key=>'val', :key2=>'val2'
=> 2

Zach