[C++-sig] Re: difficulty with has_back_reference example

Jonathan Brandmeyer jbrandmeyer at earthlink.net
Sun Jul 18 19:54:08 CEST 2004

On Sun, 2004-07-18 at 11:58, David Abrahams wrote:
> Jonathan Brandmeyer <jbrandmeyer at earthlink.net> writes:
> > On Sat, 2004-07-17 at 15:21, David Abrahams wrote:
> >> David Abrahams <dave at boost-consulting.com> writes:
> >> > See libs/python/test/back_reference.cpp in your boost distribution,
> >> > which does compile.  Would you mind posting a patch to correct the
> >> > documentation (or just checking in the fix once you know what it is
> >> > if you have checkin privs)?
> >> 
> >> The problem is that has_back_reference<T> needs to be a metafunction.
> >
> > Thanks for the diagnosis.  Rather than raise the requirement of
> > has_back_reference<T> from being a traits class to a predicate
> > metafunction, would you accept the following patch?  It basically
> > performs a metacast from a predicate traits struct to a metafuction.  I
> > will be happy to apply the right patches in either case.
> I'm afraid not.  I'm actually in the process or reworking and
> cleaning up that whole area of the code.  The metafunction protocol
> is the emergent Boost standard; has_back_reference doesn't need to
> inherit from mpl::bool_<x>, but it does need to have a nested ::type
> with a nested ::value.

OK.  I've fixed the docs.


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