Re: [boost] Submission: typelist

From: Mark Rodgers (mark.rodgers_at_[hidden])
Date: 2001-11-28 10:10:16

From: "David Abrahams" <david.abrahams_at_[hidden]>

> Actually, the  type list implementation in MPL 
> isn't the (most) interesting part. The algorithms 
> are more interesting, IMO.

Well because template metaclasses can't have member 
metafunctions, the distinction between list implementation
and algorithm is somewhat blurred.  I see size and at, 
for example, as being part of the list implementation
whereas distance and find are algorithms.  All four
are interesting :-)

The key point for me is does it matter to users whether
they write loki::length<x>::value or mpl::size<x>::value
and do they care how whatever they write is implemented?

I'd like us to agree that everyone should write 
mpl::size<x>::value, even if an initial release 
implemented this in a simple recursive manner.  When and 
if the full mpl is accepted into boost, the implementation
could change completely, but no-one would need to care.

If Andrei were to rework his type list submission so that
it matched the mpl interface, we could get it accepted 
earlier than mpl and people could begin to use it.  We 
could then go on to debate the merits of the rest of
the mpl and the alternative implementation without worrying 
that we'd already accepted a completely different and 
incompatible type list.

Mark