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How should I typedef a template class ? Something like:
typedef std::vector myVector; // <--- compiler error I know of 2 ways:
(1) #define myVector std::vector // not so good (2) template<typename T> struct myVector { typedef std::vector<T> type; }; // verbose Do we have anything better in C++0x ?
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Similarly, typedef can be used to define a structure, union, or C++ class.
Class Template Declarationtemplate <class T> class className { private: T var; ... .. ... public: T functionName(T arg); ... .. ... }; In the above declaration, T is the template argument which is a placeholder for the data type used, and class is a keyword.
For normal code, you would use a class template when you want to create a class that is parameterised by a type, and a function template when you want to create a function that can operate on many different types.
The class keyword is used to specify a generic type in a template declaration.
Yes. It is called an "alias template," and it's a new feature in C++11.
template<typename T> using MyVector = std::vector<T, MyCustomAllocator<T>>; Usage would then be exactly as you expect:
MyVector<int> x; // same as: std::vector<int, MyCustomAllocator<int>> GCC has supported it since 4.7, Clang has it since 3.0, and MSVC has it in 2013 SP4.
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