Re: [boost] BGL adjacency list container selectors

From: Jeremy Siek (jsiek_at_[hidden])
Date: 2002-03-05 18:07:14

Good points. I'll look into making what is currently used as a
"workaround" into the primary mechanism.

Cheers,
Jeremy

On Fri, 1 Mar 2002, Jens Maurer wrote:
Jens.M> Jeremy Siek wrote:
Jens.M> >
Jens.M> > The change you suggest is in fact the current approach we use to work
Jens.M> > around VC++. As to whether that approach is simpler is not so clear to me.
Jens.M> > For example, the 2nd approach requires a nested class, which could be
Jens.M> > regarded as a complication. Overall, I'd classify this NAD ;)
Jens.M>
Jens.M> > david.>  struct list_with_allocatorS {    template <class ValueType>    struct apply    {
Jens.M> > david.>       typedef typename Alloc::template rebind<ValueType>::other Allocator;
Jens.M> > david.>       typedef std::list<ValueType, Allocator> type;
Jens.M> > david.>     }; };
Jens.M>
Jens.M> Yes, I'm late at it, but I'd like to say I agree with David here.
Jens.M> Also in terms of the recent template metaprogramming discussion,
Jens.M> it appears to me that the nested class template is the way to
Jens.M> go for any situation where you'd have wanted template template
Jens.M> parameters but they were too limiting.
Jens.M>
Jens.M> What David is proposing is to have a user-defined metafunction to
Jens.M> create the list type the user wants.  Terminology-wise, this blends
Jens.M> nicely with whatever template metaprogramming aids we come up
Jens.M> with later.  In my opinion, thinking about it this way
Jens.M> ("here's a function that produces some list type") is actually
Jens.M> easier and much more straightforward than thinking in terms of
Jens.M> partial specializations.
Jens.M>
Jens.M> Also, there's no "global state" as with a (partial)
Jens.M> specialization in the boost namespace, and all the helper
Jens.M> types I need are indeed localized in the user's namespace.
Jens.M>
Jens.M> Jens Maurer

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 Jeremy Siek                          http://php.indiana.edu/~jsiek/
 Ph.D. Student, Indiana Univ. B'ton   email: jsiek_at_[hidden]
 C++ Booster (http://www.boost.org)   office phone: [phone]
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