What is a template pack?
A template parameter pack is a template parameter that accepts zero or more template arguments (non-types, types, or templates). A function parameter pack is a function parameter that accepts zero or more function arguments. A template with at least one parameter pack is called a variadic template.
What is parameter pack in C++?
Parameter packs (C++11) A parameter pack can be a type of parameter for templates. Unlike previous parameters, which can only bind to a single argument, a parameter pack can pack multiple parameters into a single parameter by placing an ellipsis to the left of the parameter name.
What is a Variadic template C++?
Variadic templates are template that take a variable number of arguments. Variadic function templates are functions which can take multiple number of arguments. Syntax for a variadic function template: : template(typename arg, typename… args) return_type function_name(arg var1, args…
How do you expand a parameter pack?
Parameter packs can only be expanded in a strictly-defined list of contexts, and operator , is not one of them. In other words, it’s not possible to use pack expansion to generate an expression consisting of a series of subexpressions delimited by operator , .
What does three dots mean in C++?
These type of functions are called variadic functions (Wikipedia link). They use ellipses (i.e., three dots) to indicate that there is a variable number of arguments that the function can process. h functions ( va_start , va_arg and va_end ) to get the specific arguments.
What is args C++?
When a function is called, the values that are passed during the call are called as arguments. The values which are defined at the time of the function prototype or definition of the function are called as parameters. These are used in function header of the called function to receive the value from the arguments.
Which is the correct example of template parameter?
For example, given a specialization Stack, “int” is a template argument. Instantiation: This is when the compiler generates a regular class, method, or function by substituting each of the template’s parameters with a concrete type.
What does Variadic mean?
From Wikipedia, the free encyclopedia. In computer science, an operator or function is variadic if it can take a varying number of arguments; that is, if its arity is not fixed.
What is Variadic generic?
Variadic generics are necessary for an Array that is generic in an arbitrary number of axes to be cleanly defined as a single class.
What is std :: forward?
std::forward This is a helper function to allow perfect forwarding of arguments taken as rvalue references to deduced types, preserving any potential move semantics involved.
What is Va_list in C?
va_list is a complete object type suitable for holding the information needed by the macros va_start, va_copy, va_arg, and va_end. If a va_list instance is created, passed to another function, and used via va_arg in that function, then any subsequent use in the calling function should be preceded by a call to va_end.
What does 3 dots mean in C++?
Its called a parameter pack and refers to zero or more template parameters: http://en.cppreference.com/w/cpp/language/parameter_pack std::size_t …Rs. is the parameter pack of type std::size_t . A variable of that type (e.g. Rs… my_var ) can be unpacked with: my_var…