[C++-sig] Boost.Python property definition question

[Jim Bosch]

On 01/31/2012 02:52 PM, Michael Wild wrote:

>> You might be able to address that by having two make_helper functions,
>> using enable_if/disable_if to select one when the return type is const
>> and the other when it isn't.  The one invoked for const returns would
>> just call make_function directly to make a getter, while the non-const
>> one would be like make_set_helper above.
>>
>>
>> Jim
>
> Sorry, I think you'll have to expand a bit on that. Do you mean that I
> can use enable_if/disable_if to select between the two implementations?
>

I think so; again, I haven't tested.

Here's the idea:

template <typename F>
typename boost::enable_if<
     boost::is_const<
         typename boost::function_types::result_type<F>::type
     >,
     bp::object
 >::type
make_helper(F f) {
     // deduce A and T ...
     return bp::make_function(
         (A const & (T::*() const))f,
         bp::return_value_policy<copy_const_reference>()
     );
}

template <typename F>
typename boost::disable_if<
     boost::is_const<
         typename boost::function_types::result_type<F>::type
     >,
     bp::object
 >::type
make_helper(F f) {
     // deduce A and T ...
     return bp::make_function(&set_helper<A,T,f>);
}

Hope that works!

Jim