Partial C++ template specialization in dependent project -

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suppose have library , multiple projects dependent on library. library headers has partial class specializations. want allow each dependent project override own partial specializations. need achieve statically performance reasons. simplified code below.

library code:

template <class a, class b, class enable=void> struct widget;  struct foo { };  template <class b> struct widget<foo, b> { };

user code:

template <class b> struct dospecialize;  template <class b> struct widget<foo, b, enable_if< dospecialize<b> >::type { };

the problem here end multiple definitions of same specialization. think need disable_if<> somewhere. how avoid this?

i'd suggest solve separating layers. library has it's own specializations , user can overwrite them if needed. if acceptable, following library code:

namespace impl {     template <class a, class b, class enable=void>     struct widget; }  template <class a, class b, class enable=void> struct widget : impl::widget< a, b > {};  struct foo { };  namespace impl {     template <class b>     struct widget<foo, b>     {     }; }

and user code stays is.


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