From: Hal Fulton <hal9000@...>
Date: 2003-09-09T04:00:32+09:00
Subject: Re: ANN: MetaTags 1.0

why the lucky stiff wrote:
> On Monday 08 September 2003 12:08 pm, dblack@superlink.net wrote:
> 
>>Namely, the idea of an extensible %_{} syntax, so that one could
>>define the behavior of %y{}, %x{}, and so on from within a Ruby
>>program or extension.
>>
>>Perhaps someone steeped in the ways of the parser could comment on
>>how hard this would be (up to and including impossible).
>>
> 
> 
> this wouldn't be much of a problem.  right now there's a 'default' case on a 
> switch in parse.y:
> 
>           default:
>         yyerror("unknown type of %string");
>         return 0;
> 
> establish a USERSTR set of tokens and node types.  (you can follow XSTR or 
> DXSTR around to see how.)  Then, in rb_eval, add a case for NODE_MISCSTR, 
> which could check for the character in a global hash, passing the string 
> contents into a proc associated with that character.  return the result of 
> the proc call from rb_eval.
> 
> the %y{...} hack could become:
> 
>    add_delimited_prefix( 'y' ) do |str|
>       YAML::load( str )
>    end

Much easier than I thought. I'll bet there are some gotchas,
though.

Matz??

Hal