[boost] Re: [lambda]/[spirit-phoenix] Lazyevaluation+expressiontemplates

From: Fernando Cacciola (fcacciola_at_[hidden])
Date: 2003-04-06 20:58:38

"Joel de Guzman" <djowel_at_[hidden]> escribió en el mensaje
news:022601c2fb12$0ae7c620$0100a8c0_at_kim...
> Fernando Cacciola wrote:
> > Hi,
> >
> > First question: I see that there is a phoenix subdirectory
> > under both boost/spirit and lib/spirit; does this mean
> > that pheonix is distributed with boost 1.30.0? or only part of it?
>
> There will be an LL/Phx merger. I hope it will be soon. That
> depends a lot on which is the least compiler to support. Right
> now, I have the core up and running on VC7 but ICEs on VC6.
> Either I leave VC6 behind (now that 7.1 is imminent), or I
> spend more time hunting by trial and error. The new LL/Phx
> merger is MPL based.
>
I'm, looking fwd to it!

> BTW, Borland works as it does in Phoenix as do a lot more
> compilers:
>
> http://spirit.sourceforge.net/wiki/index.php?page=Compiler+Table
>
> So the question is *to-vc6-or-not-to-vc6*, please send in your votes.
>
I prefer to have a tool that works only on new compilers than not to have it
at all.

> Second question: I'm trying to do something which I
> > think could be done with some of the functional programming
> > libraries and tools available here at boost, perhaps
> > in combination with other tools from elsewhere.
>
> [snip]
>
> Ah..Lazy-evaluation... This was asked in the past. Phoenix named
> placeholders: Phoenix+boost::function :-)...
> This link might be of interest to you:
>
>
http://article.gmane.org/gmane.comp.parsers.spirit.general/3393/match=placeh
older+cpp
>
> This feature will hopefully, if Jaakko agrees, be part of the new
> merger.
>
I just swa it, looks great!

>
> I'm heavily investigating *true* lazy evaluation, not to be confused
> with partial evaluation that's currently done in LL and Phoenix.
> To avoid confusion, I should change everything "lazy" in the Phx
> docs to probably be "deferred". These are subtly different concepts.
>
Intereseting.... I think to remeber having read about a C++ framework
with true lazyiness in one of the FC++ papers (but not in FC++ itself).
If I get to remember it, I'll let you now.

BTW, I actually need 'deferred' eval for my purposes, not truly lazy, so the
"named-placeholder+function object" trick would do I guess.

Thanks,

Fernando Cacciola