christopher diggins wrote:
When inheriting from an STL container the constructors and local typedefs need to be redeclared. For instance the vector contract class at http://www.ootl.org/pwc/pwc_vector.hpp.htm .
Only if you want to use them inside the class without qualification.
It seems to me that it would be very useful to have a single macro for each of the different STL containers to ease inheritance of them. Does Boost already have something like that? If not would anyone else want something like this for Boost? Or am I really missing something basic here, and this is a bad idea for some obscure C++ reason?
I think publicly inheriting from a class that isn't designed for inheritance is a bad idea. There are type safety problems, non-virtual destructors, slicing etc. It's generally better to use composition, or perhaps protected or private inheritance with 'using' statements to make the appropriate functions public.
i.e.
#define BOOST_STL_VECTOR_OVERRIDE(NAME, ELEMENT) /* */ \ typedef std::vector<ELEMENT> inherited; \ typedef typename inherited::size_type size_type; \ typedef typename inherited::reference reference; \ [snip]
I don't know how portable this is, but if you're using single inheritance, you might be able to write: #define BOOST_STL_VECTOR_OVERRIDE(NAME) /* */ \ typedef typename NAME::value_type value_type; \ typedef typename NAME::allocator_type; \ typedef std::vector<value_type, allocator_type> inherited; Daniel