Re: [boost] Overloading a function taking a boost::function

From: Douglas Gregor (gregod_at_[hidden])
Date: 2002-05-11 10:15:09

On Saturday 11 May 2002 09:12 am, you wrote:
> I appreciate your input, and this is indeed another way to look at the
> problem. But I don't really thing it is easier to write ArietyTrait than
> it is to write make_function. (It might be more reusable though???)
>
> Also, I forgot to mention that I'm using MSVC6 so no partial
> specialization.
>
> :(
>
> Dirk Gerrits

You can do the same without partial specialization using function overloading:

template<typename R>
inline boost::function0<R> make_function(R (*f)())
  { return boost::function0<R>(f); }

template<typename R, typename T1>
inline boost::function1<R, T1> make_function(R (*f)(T1))
  { return boost::function1<R, T1>(f); }

template<typename R, typename T1>
inline boost::function1<R, T1> make_function(R (T1::*f)())
  { return boost::function1<R, T1>(f); }

// etc...

Of course, this style only works for free and member functions. We'd need 
something like ArityTraits to handle arbitrary function objects. That's the 
reason that make_function never really made it: we don't have a good set of 
function object traits to work with. 

If we _did_ have a working set of function traits, it would be possible to 
make Boost.Function objects implicitly constructed only from function objects 
that are callable by the Boost.Function object.

        Doug