Search results
Results from the WOW.Com Content Network
The variadic template feature of C++ was designed by Douglas Gregor and Jaakko Järvi [1] [2] and was later standardized in C++11. Prior to C++11, templates (classes and functions) could only take a fixed number of arguments, which had to be specified when a template was first declared.
To elaborate on the above example, consider a base class with no virtual functions. Whenever the base class calls another member function, it will always call its own base class functions. When we derive a class from this base class, we inherit all the member variables and member functions that were not overridden (no constructors or destructors).
The problem is that, while virtual functions are dispatched dynamically in C++, function overloading is done statically. The problem described above can be resolved by simulating double dispatch, for example by using a visitor pattern. Suppose the existing code is extended so that both SpaceShip and ApolloSpacecraft are given the function
C++14 allows the creation of variables that are templated. An example given in the proposal is a variable pi that can be read to get the value of pi for various types (e.g., 3 when read as an integral type; the closest value possible with float, double or long double precision when read as float, double or long double, respectively; etc.).
Note the double meaning of the word variable and the difference between arguments and variables in functional programming and term rewriting. For example, a term (function) can have three variables, one of them a hedge, thus allowing the term to take three or more arguments (or two or more if the hedge is allowed to be empty).
The image of a function f(x 1, x 2, …, x n) is the set of all values of f when the n-tuple (x 1, x 2, …, x n) runs in the whole domain of f.For a continuous (see below for a definition) real-valued function which has a connected domain, the image is either an interval or a single value.
A tuple can be considered a generalization of a struct's member variables. The C++11 version of the TR1 tuple type benefited from C++11 features like variadic templates. To implement reasonably, the TR1 version required an implementation-defined maximum number of contained types, and substantial macro trickery.
In C++20, the std::bit_cast function allows type punning with ... there can be several variables in a variant record's ... for example, combine two enum values of a ...