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

From: Joel de Guzman (djowel_at_[hidden])
Date: 2003-04-04 20:23:57

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.

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.

> 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=placeholder+cpp

This feature will hopefully, if Jaakko agrees, be part of the new
merger. 

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.

-- 
Joel de Guzman
joel at boost-consulting.com
http://www.boost-consulting.com
http://spirit.sf.net