Re: [boost] Interest for a perl6-like-junctions-class?

From: David Abrahams (dave_at_[hidden])
Date: 2005-08-18 08:41:05

Rob Stewart <stewart_at_[hidden]> writes:

> I uploaded some fixes to multivalues.zip:
>
>  - Workaround for BCB's lack of EBO
>
>  - Fixed some overzealous searches/replaces
>
>  - Eliminated SFINAE from test program
>
>  - Moved some tests out of the macros to assist in debugging,
>    should anyone have problems with support in a particular
>    compiler.
>
> Some questions:
>
>  - What operator(s) should we use to delimit user-defined
>    predicates?  Here are some interesting candidates:
>
>    if (any_of(...) << some_predicate() >> 5)... // 1
>
>    if (any_of(...) < some_predicate() > 5)... // 2
>
>    if (any_of(...) ^ some_predicate() ^ 5)... // 3
>
>    if (any_of(...) / some_predicate() / 5)... // 4
>
>    1 seems pretty good because the two-character operators stand
>    out well.  2 works pretty well, but I'm concerned that the
>    operators may get lost if the predicate is a specialization of
>    a template type; the template argument list uses the same
>    tokens.  (1 is better in that case because of the doubled
>    tokens.)

None of them look right to me.  Unless you close up the spaces next to
some_predicate(), they appear to be doing what the usual C++ operators
do.  a < b looks like less-than; a <b  immediately starts to suggest
something else.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com