Effective C + + notes

Chapter 7 templates and generic programming Item 41

For template parameters, the interface is implicit and only when instantiated, does it check that the actual template type supports the interface in the template

Item 42

template <typename C>void print2nd(const C& container) {    C::const_iterator* x;}

As in the code, if you do not prefix const::iterator with TypeName, the compiler will not assume that it is a type, which will create ambiguity. Perhaps const_iterator is a static variable of a class, resulting in an explanation of multiplying by X.

However, TypeName can only be used with nested dependent type, such as

template <typename C>void f(const C& container, typename C::iterator iter);

C is automatically deduced, and only ITER needs to mark it as type.

Effective C + + notes