Le 27/08/12 02:55, Lorenzo Caminiti a écrit :
Le 26/08/12 18:24, Lorenzo Caminiti a écrit :
Hi,
On Sun, Aug 26, 2012 at 2:16 AM, Vicente J. Botet Escriba <vicente.botet@wanadoo.fr> wrote:
Hi,
First of all, thanks Lorenzo for your work on pre-processor programming. With this library, you have showed to me how far the pre-processing can go in terms of expressiveness. Welcome :)
I have some questions before doing a complete the review:
= C++11 compatibility =
* Does the library use c++11 features when available? I was thinking e.g. on the emulated virtual specifiers. BTW, I think the "new" virtual specifier was removed from the standard, but maybe I'm wrong. * I think the library don't allow to declare C++11 specific classes/function. E.g * variadic templates * noexcept functions * constexpr functions * class/function attributes The library is written for C++03 for now, while it emulates some C++11 features for C++03, the library doesn't support all C++11 features and doesn't take advantage (go native) of them when available instead of the emulated features. I am planning to extend the library to support C++11 (the declaration syntax should be extendible without any problem). I've added a ticket https://sourceforge.net/apps/trac/contractpp/ticket/61 I guess it will be better to have a ticket for each planned feature, so that they can be delivered one by one. For people that are using C++11, this could be a show-stopper for the library adoption, and IMO there are more and more that are moving to C++11. Once I start supporting C++11 (which I could do before an eventual Boost release), it should be easy enough to support *all* C++11 extra declaration features at once. In most cases the lib has to simply
On Sun, Aug 26, 2012 at 10:00 AM, Vicente J. Botet Escriba <vicente.botet@wanadoo.fr> wrote: parse the pp syntax and generate the C++11 native code under-nit.
BTW, I have not see any example using exception specifications using 'throws'. Does the library support them? Yes, for example:
http://contractpp.svn.sourceforge.net/viewvc/contractpp/releases/contractpp_...
http://contractpp.svn.sourceforge.net/viewvc/contractpp/releases/contractpp_...
http://contractpp.svn.sourceforge.net/viewvc/contractpp/releases/contractpp_... Thanks, I have not yet read this part.
Could you confirm? and if not, could you tell us if you have a plan to support them?
= Postconditions result =
"Postconditions can access the function return value by declaring a variable of type |auto| and assigning it to the |return| keyword (the variable name is arbitrary but |result| is often used)."
What prevent the library to the use of return instead of an auto variable
postcondition( // Postconditions. auto old_value = CONTRACT_OLDOF value, // Old value(s). value == old_value + 1, // Assertion(s)... return == old_value ) This won't work if return is not the 1st token:
old_value == return 3 + return myfync(return) etc
because there's no way the preprocessor can skip the leading tokens given that they are unknown :( and they could contain symbols. I will clarify this point in the rationale. OK. I understand.
instead of
postcondition( // Postconditions. auto result = return, // Result value. auto old_value = CONTRACT_OLDOF value, // Old value(s). value == old_value + 1, // Assertion(s)... result == old_value )
=Constant assertions =
I would expect that the old are always const so the following
postcondition( auto old_even = CONTRACT_OLDOF even, auto old_odd = CONTRACT_OLDOF odd, // `[old_]even` and `[old_]odd` all `const&` within assertions. const( even, old_even ) even == old_even + 2, const( odd, old_odd ) odd == old_odd + 2 ) old_... are const but you need to specify them in const( ... ) so they can be accessed by the constant-assertion boolean condition:
const( var1, var2, ... ) boolean-condition-using-var1-var2-... Why? Because constant-assertions are implemented using local functions which have such a limitation. Essentially, constant-assertions are local function's constant blocks: http://www.boost.org/doc/libs/1_51_0/libs/local_function/doc/html/boost_loca... I'll document this rationale.
I understand now why all the used variables need to be declared. I don't think I will use it to prevent from constness errors. Note that reversing the arguments in assertions/checks is a good practice: old_odd + 2 == odd How this const local functions relates to c++11 lambda expressions? Best, Vicente