[Quantlib-dev] c++0x

[Peter C. <pca...@gm...>]

Hi Luigi, all,

we discussed compiling the core lib under the c++11 standard (e.g. with
g++ -std=c++0x). This produces some errors which can be fixed easily
(keeping backward compatibility):

https://github.com/pcaspers/quantlib/commit/5b32b7705530264551e0622d0a2673813067be5b

What is left is a bunch of warnings saying that std::auto_ptr is
depricated under c++11, the replacement being std::unique_ptr. A
possible solution is to replace the auto_ptr in the source by unique_ptr
(thus upgrading the code to c++11 already) and replace the unique_ptr by
auto_ptr again in case that compilation is done under c++ versions <
11. I have done this here

https://github.com/pcaspers/quantlib/commit/3e47a82a936112f12e3bb502292833d860f5aac9

with a #define in qldefines.hpp resetting the pointers to auto_ptr again
based on the boost macro BOOST_NO_CXX_SMART_PTR. Unfortunately this
macro is available only in later boost versions so if one uses an older
one and provides no c++11 support he or she will get errors. Therefore
the following solution might be better

https://github.com/pcaspers/quantlib/commit/6db965375b02094a7ea0da4e48efd7e0a1b8fd85

using the __cplusplus macro to identify c++11. However since gcc sets
this macro simply to 1 in versions 4.6 (should be solved starting in
4.7), I had to add another criterion for gcc based on
__GXX_EXPERIMENTAL_CXX0X_.

For msvc 2010 the __cplusplus is also not 201103L but still 199711L. This
seems also to be the case in 2012 and this specific case was reported as a bug to
Microsoft,

http://connect.microsoft.com/VisualStudio/feedback/details/763051/a-value-of-predefined-macro-cplusplus-is-still-199711l

though not solved yet. Therefore I added a direct test on msvc 2010 or
higher versions based on _MSC_VER 

https://github.com/pcaspers/quantlib/commit/796beb89e2a707f951b77869bf869694e67ac769

This final solution should work for all versions of msvc and gcc. I can not check other
compilers however.

Since the #define seems a bit like a dirty hack we also thought of a
typedef. But then we would need a template typedef which is available only in
c++11 again and a metaprogramming-like workaround a la

template<class T> struct PTR {
    typedef std::unique_ptr<T> Type;
};

PTR<double>::Type a(new double(0.0));

does not seem to improve the code either.

Do you think we should do the upgrade to c++11 like propsed above or is there
maybe a better solution (I bet there is...). Or should we defer the
upgrade until a later release ? I personally would very much like to be
able to compile under c++11 without warnings already now.

Thank you
 Peter