scoped_ptr -> Loki -> MPL dependency chain [was typelist]

From: Beman Dawes (bdawes_at_[hidden])
Date: 2001-11-28 15:25:17

At 12:40 PM 11/28/2001, Mat Marcus wrote:

 >
 >* If we reimplement the boost smart pointers in terms of Loki, and we
 >reimplement Loki typelists in terms of mpl, does that meant that
 >application programmers have to be mpl/Meta-STL aware when debugging
 >simple scoped pointers?

That's a good question.  We (and the standards committee) would have to be 
sure to specify the more common pointers (scoped_ptr, auto_ptr, shared_ptr) 
in a way that ensured the "as if" rule applies.

In other words, if a implementor decided to implement these common pointers 
directly, rather than by typedef template, he or she should be free to do 
so.

 >* I would like to see some more concrete discussion. General
 >philosophizing about the merits of different libraries has a low
 >signal to noise ratio.
 >
 > We have to consider both interface and
 >implementation. For example, could we shed some light on the mpl
 >interface by looking at some example code/use cases?

Yes, for sure.  Some of the examples posted so far (Mark Rodgers' 
loki::length vs mpl::size) make it look like the differences are 
trivial.  More examples would be very helpful.

 > Perhaps some of
 >Andrei's typelist applications could be rewritten in mpl to give us a
 >better feel for mpl's idioms. I would also be interested in seeing
 >some examples illustrating any of the facilities that Dave mentioned
 >in an earlier post:
 >
 >
 >At 7:59 PM -0500 11/27/01, David Abrahams wrote:
 >>1. Algorithms can be used with different compile-time sequence 
structures
 >>and implementations
 >>
 >>2. Function composition
 >>
 >>3. Argument binding
 >>
 >>4. A far-thinking design for metafunctions which will probably allow a
 >>meta-lambda facility
 >>
 >>5. Lifts the need for the user to deal explicitly with loopn termination 

 >in
 >>a separate piece of code (the specialization).
 >>
 >>6. A convenient way to specify type lists without macros

Yes, I'd like to see those too.

--Beman