Search results
Results From The WOW.Com Content Network
In C++11, this technique is known as generalized constant expressions (constexpr). [2] C++14 relaxes the constraints on constexpr – allowing local declarations and use of conditionals and loops (the general restriction that all data required for the execution be available at compile-time remains).
Expression templates are a C++ template metaprogramming technique that builds structures representing a computation at compile time, where expressions are evaluated only as needed to produce efficient code for the entire computation. [1]
C++26 is the informal name for the version of the International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC) 14882 standard for the C++ programming language that follows C++23. The current working draft of this version is N4981.
C++11 introduced template aliases, which act like parameterized typedefs. The following code shows the definition of a template alias StrMap. This allows, for example, StrMap<int> to be used as shorthand for std::unordered_map<int,std::string>.
However, C++11 constexpr functions could only contain a single expression that is returned (as well as static_asserts and a small number of other declarations). C++14 relaxes these restrictions. Constexpr-declared functions may now contain the following: [3] Any declarations except: static or thread_local variables.
A third way is by declaring and defining a variable as being "constant". A global variable or static variable can be declared (or a symbol defined in assembly) with a keyword qualifier such as const, constant, or final, meaning that its value will be set at compile time and should not be changeable at runtime. Compilers generally put static ...
Here, attempting to use a non-class type in a qualified name (T::foo) results in a deduction failure for f<int> because int has no nested type named foo, but the program is well-formed because a valid function remains in the set of candidate functions.
The technique was formalized in 1989 as "F-bounded quantification."[2] The name "CRTP" was independently coined by Jim Coplien in 1995, [3] who had observed it in some of the earliest C++ template code as well as in code examples that Timothy Budd created in his multiparadigm language Leda. [4]