Re: [Boost-users] Re: starting to learn Boost MPL and type_trait

Jonathan Turkanis wrote:

Sharon Galtzur wrote:

...

Thanks for the reply. The thing i dont understand is this : template <class T> void f(int (T::*)(int)) will match any member function with specific signature (receiving int and returning int). But not all classes have such function. So in this case how will a class F { } be matched ?

No member of the given type need exist for the pointer-to-member type to be well-formed. Consider:

struct C { };

typedef void (C::*mem_fun) (std::string);

The later expression defines a type which can have no instances, <snip>

Actually it can: struct D : C { void foo(std::string); }; mem_fun mf = static_cast(&D::foo); Not that I'd recommend doing that, as it invites type errors. Ben.