Re: [boost] [parameter] Avoiding the forwarding problem w/additional overloads

From: Daniel Wallin (dalwan01_at_[hidden])
Date: 2006-02-09 11:33:36

1.34 will feature new macros in Boost.Parameter that have a
significantly improved interface. Some of the syntax is demonstrated in
this test:

http://cvs.sourceforge.net/viewcvs.py/*checkout*/boost/boost/libs/parameter/test/preprocessor.cpp

They also support in/out parameter overload generation, like what you
have here. The syntax for this will be:

  BOOST_PARAMETER_FUNCTION((int), f, tag,
      (required
        (out(tester), *)
         ^^^
        (name, *)
      )
  )

Cromwell Enage wrote:
> I've implemented a new macro, BOOST_PARAMETER_FUN2,
> that uses approach #3 mentioned in
> <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2002/n1385.htm>.
>  For example, the BGL implementation of Dijkstra's
> algorithm
> <http://www.boost.org/libs/graph/doc/dijkstra_shortest_paths.html>
> can now be declared as:
> 
> struct dijkstra_parameters
>   : parameter::parameters<...>
> {
> }
> 
> BOOST_PARAMETER_FUN2(
>     void
>   , dijkstra_shortest_paths
>   , (0)(0)(1)(1)(0)(0)(0)(0)(0)(0)(1)(1)
>   , 2
>   , dijkstra_parameters
> )
> {
>     ...
> }
> 
> Each element in the Boost.Preprocessor sequence
> corresponds to a positional argument.  If the element
> is set to 1, the argument is bound to an "out"
> parameter; otherwise it is bound to an "in" parameter.
>  The size of the sequence is, of course, the total
> number of arguments accepted by the function.

-- 
Daniel Wallin