From: gabriele renzi <surrender_it@...>
Date: 2005-10-14T02:56:54+09:00
Subject: Re: Default argument values for blocks

Austin Ziegler ha scritto:
> On 10/13/05, Christophe Grandsire <christophe.grandsire@free.fr> wrote:
> 
>>Yacc does. Even the simple { |a,b=1| a*b } fails because Yacc treats it as { |
>>a,b=(1| a*b) }. And that *cannot* be solved in the current state of Yacc. The
>>problem is that there doesn't seem to be *any* solution that solves both this
>>problem and the problem of allowing bitwise or's in default arguments, short of
>>renaming the bitwise or, which would be such a compatibility break that it isn't
>>worth contemplating.
>>
>>This is at least my understanding of the problem.
> 
> 
> Is there any particular reason that we can't use a different parser,
> e.g., Coco or something else? Surely there's got to be something
> better than Yacc by now.
> 
> -austin

I remember matz talking about ANTLR long time ago, AFAIR he said 
something realted to ANTLR, I think he said that while it could be fast, 
thread safe and a lot of nice things there were some problems on the 
programmer side (maybe lack of knowledge, I can't remember well).

OTOH I think the people trying to rewrite a ruby parser with COCO had 
some problems too (think of ParseTree).