From: Phrogz <phrogz@...>
Date: 2007-11-05T22:45:19+09:00
Subject: Re: def blah do |x| -- alternate method definition syntax

On Nov 5, 4:59 am, joe07...@gmail.com wrote:
> Thanks matz and all. The define_method() trick hadn't occurred to me  
> -- almost the same, indeed. Why couldn't block parameter syntax be  
> extended to accept optional args: do |x, y=0| ? I Realize that this is  
> only meaningful for the hypothetical def usage, but come to think of  
> it I see no reason blocks couldn't accept optional args in cases where  
> they're .called().

Because the | operator exists, and there are some edge cases where it
would be hard to determine when the block had ended. Something like:

  foo{ |x, y=0| 1+6|7 }

could be either:
  foo{ |x, y=0| (1+6|7) }
or
  foo{ |x, y=((0|1)+6)| 7 }


IIRC, it's not just that such edge cases exist (where a sane human
could possibly make a choice to disallow certain otherwise-legal
syntax), but that it's very hard or impossible to adjust the syntax
lexer to allow them.