On 20 Aug 2009, at 23:57, Scott McMurray wrote:
2009/8/20 Edward Grace <ej.grace@imperial.ac.uk>:
if O is compatible with the concept of a functor and O returns a type that can be converted to a float, then we are good to go -- otherwise I'd like an intelligible error.
If, for example, O is of the type 'void (*)()' I'd like it (the compiler) to spit out, "The function pointer of type O must of signature float (*)()"
Sounds like you want something like the MPL_ASSERT example at [1] along with the result_of metafunction[2].
[1] http://www.boost.org/doc/libs/1_39_0/libs/mpl/doc/refmanual/ assert.html
[2] http://www.boost.org/doc/libs/1_39_0/libs/utility/ utility.htm#result_of
Sorted! It turns out that the other problem I was having as also not including is_same.hpp.... Thanks for the pointers (excuse the C pun). Curiously, littering my code with these assertions has now highlighted some (genuine) wrinkles that I hadn't spotted before. Regards, -ed ------------------------------------------------ "No more boom and bust." -- Dr. J. G. Brown, 1997