Defined Terms

class template Definition from which specific classes can be instantiated. Class templates are defined using the template keyword followed by a comma-separated list of one or more template parameters enclosed in < and > brackets, followed by a class definition.

default template arguments A type or a value that a template uses if the user does not supply a corresponding template argument.

explicit instantiation A declaration that supplies explicit arguments for all the template parameters. Used to guide the instantiation process. If the declaration is extern, the template will not be instantiated; otherwise, the template is instantiated with the specified arguments. There must be a nonextern explicit instantiation somewhere in the program for every extern template declaration.

explicit template argument Template argument supplied by the user in a call to a function or when defining a template class type. Explicit template arguments are supplied inside angle brackets immediately following the template’s name.

function parameter pack Parameter pack that represents zero or more function parameters.

function template Definition from which specific functions can be instantiated. A function template is defined using the template keyword followed by a comma-separated list of one or more template parameters enclosed in < and > brackets, followed by a function definition.

instantiate Compiler process whereby the actual template argument(s) are used to generate a specific instance of the template in which the parameter(s) are replaced by the corresponding argument(s). Functions are instantiated automatically based on the arguments used in a call. We must supply explicit template arguments whenever we use a class template.

instantiation Class or function generated by the compiler from a template.

member template Member function that is a template. A member template may not be virtual.

nontype parameter A template parameter that represents a value. Template arguments for nontype template parameters must be constant expressions.

pack expansion Process by which a parameter pack is replaced by the corresponding list of its elements.

parameter pack Template or function parameter that represents zero or more parameters.

partial specialization Version of a class template in which some some but not all of the template parameters are specified or in which one or more parameters are not completely specified.

pattern Defines the form of each element in an expanded parameter pack.

template argument Type or value used to instantiate a template parameter.

template argument deduction Process by which the compiler determines which function template to instantiate. The compiler examines the types of the arguments that were specified using a template parameter. It automatically instantiates a version of the function with those types or values bound to the template parameters.

template parameter Name specifed in the template parameter list that may be used inside the definition of a template. Template parameters can be type or nontype parameters. To use a class template, we must supply explicit arguments for each template parameter. The compiler uses those types or values to instantiate a version of the class in which uses of the parameter(s) are replaced by the actual argument(s). When a function template is used, the compiler deduces the template arguments from the arguments in the call and instantiates a specific function using the deduced template arguments.

template parameter list List of parameters, separated by commas, to be used in the definition or declaration of a template. Each parameter may be a type or nontype parameter.

template parameter pack Parameter pack that represents zero or more template parameters.

template specialization Redefinition of a class template, a member of a class template, or a function template, in which some (or all) of the template parameters are specified. A template specialization may not appear until after the base template that it specializes has been declared. A template specialization must appear before any use of the template with the specialized arguments. Each template parameter in a function template must be completely specialized.

type parameter Name used in a template parameter list to represent a type. Type parameters are specified following the keyword typename or class.

type transformation Class templates defined by the library that transform their given template type parameter to a related type.

variadic template Template that takes a varying number of template arguments. A template parameter pack is specified using an elipsis (e.g., class. . ., typename. . ., or type-name. . . ).