Re: [boost] Re: Re: Adding Loki to Boost (reprise)

From: David A. Greene (greened_at_[hidden])
Date: 2002-04-12 11:48:35

Andrei Alexandrescu wrote:

> do so - a time when I need, and asked, for boost's support (without
> getting any, sigh). Let me restate there is nothing personal about

Andrei, there are plenty of people here who want to see parts of
Loki in Boost.  I am not an "expert" Boost developer and therefore
don't meet your ideal criteria for helping.  Few people on this
list do.  I'd love to contribute, but I'm not familiar with Boost's
build system.  Tell me what I can do and I'll see if I can get time
to do it.  I'm writing a dissertation too.  :)

> This being said, it is a surprise to me that there's no consensus that
> MPL's find_if is much more complicated than the version I posted. To
> me it is obvious. It is so obvious, that I thought there's going to be
> no discussion about it. I thought the argument in MPL's favor is that
> it makes complicated things simple. A convincing argument would be:
> "Well, I agree that count_if is big and hairy, and can't be understood
> but by an MPL savvy, but look, here's a nice example of MPL solving a
> real, hard problem, in a very cool manner! How about that?" So it
> seems like we can't find agreement on the simplest premises.

I agree with this.  The MPL count_if example is really confusing.  I
have yet to see a convincing example of why such convolutions are
necessary.  Some have alluded to complex metaprogramming problems
more easily solved with MPL/"iteration" that recursion/pattern
matching but I haven't seen them.  There have been several calls
for implementations of Loki facilities in MPL and to my knowledge,
not one has been posted.

MPL may be nice, I don't know.  It's tough for me to begin using
it without documentation.  Such information has been promised for
quite some time now and it seems it's still not up-to-date.

I hope MPL makes it into Boost.  A metaprogramming library would
be extremely useful.  Can MPL support algorithms written using
recursion?  If it can handle recursion as well as iteration, I'd
be happier.

                                     -Dave

-- 
"Some little people have music in them, but Fats, he was all music,
  and you know how big he was."  --  James P. Johnson