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The curiously recurring template pattern (CRTP) is an idiom, originally in C++, in which a class X derives from a class template instantiation using X itself as a template argument. [1] More generally it is known as F-bound polymorphism , and it is a form of F -bounded quantification .
For this purpose, the C++11 standard library defines the smart pointer classes std::unique_ptr for single-owned objects and std::shared_ptr for objects with shared ownership. Similar classes are also available through std::auto_ptr in C++98, and boost::shared_ptr in the Boost libraries. Also, messages can be sent to network resources using RAII.
In computer programming, initialization or initialisation is the assignment of an initial value for a data object or variable. The manner in which initialization is performed depends on the programming language, as well as the type, storage class, etc., of an object to be initialized.
When T has the nested type foobar defined, the instantiation of the first test works and the null pointer constant is successfully passed. (And the resulting type of the expression is yes .) If it does not work, the only available function is the second test , and the resulting type of the expression is no .
For example, the template base class in the Factorial example below is implemented by matching 0 rather than with an inequality test, which was previously unavailable. However, the arrival in C++11 of standard library features such as std::conditional has provided another, more flexible way to handle conditional template instantiation.
Providing a static method that returns a reference to the instance; The instance is usually stored as a private static variable; the instance is created when the variable is initialized, at some point before when the static method is first called. This C++23 implementation is based on the pre-C++98 implementation in the book [citation needed].
In a software design pattern view, lazy initialization is often used together with a factory method pattern. This combines three ideas: Using a factory method to create instances of a class (factory method pattern) Storing the instances in a map, and returning the same instance to each request for an instance with same parameters (multiton pattern)
Some languages require that method be specifically declared as virtual (e.g. C++), and in others, all methods are virtual (e.g. Java). An invocation of a non-virtual method will always be statically dispatched (i.e. the address of the function call is determined at compile-time).