Hello all, Consider the following C++0x-like example (inspired by ConceptC++ http://www.generic-programming.org/languages/conceptcpp/tutorial/ and C++ Contract Programming proposal n1962): // Example strangely uses pointers instead of iterators just to have preconditions. template<std::CopyConstructible T> requires Addable<T>, Assignable<T> // Concepts. precondition { first; last; } // Pointers not null. postcondition (total) { total == result; } // Returning result. T sum(T* first, T* last, T result) { for (; first != last; ++first) result = result + *first; return result; } What do you think of the following macro that implementes this in ISO standard C++ while keeping the above C++0x-like syntax by wrapping it within a preprocessor sequence? BOOST_CPP0X_FUNCTION( (template)( (std::CopyConstructible)(T) ) (requires)( (Addable<T>) (Assignable<T>) ) (precondition)( (first) (last) ) (postcondition)(total)( (total == result) ) (T) (sum)( (T*)(first) (T*)(last) (T)(result) ) ({ for (; first != last; ++first) result = result + *first; return result; }) ) The idea is that using the preprocessor I can parse the specified signature-sequence so I have all the tokens I need to declare/define the C++ function plus I can add the concepts (Boost.Concept), contracts (Boost.Contract), named parameters (Boost.Parameter), etc. Furthermore, the syntax of signature-sequence can be any valid preprocessor sequence that uses words (but not symbols) for keywords -- e.g., (requires) and (preconditions) are OK but (=) is not. This way I can define the signature-sequence syntax to closely match the syntax of C++0x (for concepts) and of other C++ standard proposals (like n1962 for contracts). DISCLAIMER: I think this is possible but I would need to try to implement it in order to be 100% sure and to identify possible limitations. Regards, Lorenzo P.S. I started considering this in reference to a previous email thread "Re: [boost] [contract] Contract Programming Library": On Sat, Feb 13, 2010 at 9:44 AM, Lorenzo Caminiti <lorcaminiti@gmail.com> wrote:

On Fri, Feb 12, 2010 at 3:39 AM, Andrzej Krzemienski <akrzemi1@gmail.com> wrote:

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I would be very interested in trying such a library. I have one it is inevitable, etc., but.. read on. I know at least one library in Boost that also spoils function declarations in order to provide additional functionality: Concept Check library; they may be others too (MPL?). My suggestion is that if there are (or will be) libraries that require spoiling function declarations, they should all provide the same "spoiled" syntax. Otherwise I will be always asking "how do I declare a function in this library?". It would be very convenient if Boost provided one alternative function definition syntax that when used would enable all its libraries to work. I agree. However, in the past I did look into harmonizing my library API with the ones of Boost.ConceptCheck and/or Boost.Parameter but it did not seem feasible... I will double check it.