Re: [lex][boost 1.44] 2 oddities

> >> Oddity #2:  It seems that I have to define
> >> assign_to_attribute_from_iterators<> for new types, even if I define
> >> a semantic action that does the assignment.
> >
> > Yes, that's true. It's the only way the lexer could know how to
> > convert a certain input character sequence into your type. Or do I
> > misunderstand something?
> 
> No, I was just making sure that *my* understanding of that was correct.
> 
> >> This further means that any
> >> semantic action [_val = ...] is useless, because the conversion will
> >> happen later and overwrite the token's value anyway, right?
> >
> > Hmmm, I think these two things are unrelated. The conversion from the
> > input iterators to your type is one thing, while the assignment inside
> > the semantic action is another one. Could you elaborate why you
> > believe the semantic action to be useless?
> 
> To me, the fact that they are unrelated leads to some slightly wonky
> behavior.  For instance if I:
> 
> (1) define an assignment to the token value in a semantic action,
> (2) I still have to specialize assign_to_attribute_from_iterators<>,
> which is fine, except that
> (3) my specialization of assign_to_attribute_from_iterators<> gets invoked
> at parse-time, overwriting the assignment I did at lex-time (1).
> 
> Am I misunderstanding how it works?  That was the behavior I saw, if I'm
> not mistaken.

Seems I misunderstood. Are you talking about a semantic action in the lexer
or one in the parser?

Regards Hartmut
---------------
http://boost-spirit.com




------------------------------------------------------------------------------
Beautiful is writing same markup. Internet Explorer 9 supports
standards for HTML5, CSS3, SVG 1.1,  ECMAScript5, and DOM L2 & L3.
Spend less time writing and  rewriting code and more time creating great
experiences on the web. Be a part of the beta today
http://p.sf.net/sfu/msIE9-sfdev2dev