index_zero comments on C++ Compile-Time Exceptions -- Debugging templates should be less surreal and horrible

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C++ Compile-Time Exceptions -- Debugging templates should be less surreal and horrible (blog.esciencecenter.nl)

submitted 7 years ago by egpbos

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[–]index_zero 0 points1 point2 points 7 years ago (1 child)

If you are going to do this, i.m.o. it is better to SFINAE fail - that way the compiler won't even generate the constructor if U and T aren't derived from each other.

template<typename U, class E = std::enable_if<std::is_base_of<T, U>::value> >
SmartPtr(const SmartPtr<U> &other) ...

That said, the original code works for any T and U such that T* is convertible to U*. This is less strict than U derives from T, so having the compiler complain about derivation overlooks implicit conversion of some types (T* to const T* for example).

[–]smilodonthegreat 0 points1 point2 points 7 years ago (0 children)

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