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Metafunction Class

Summary

A metafunction class is a certain form of metafunction representation that enables higher-order metaprogramming. More precisely, it's a class with a publicly-accessible nested Metafunction called apply. Correspondingly, a metafunction class invocation is defined as invocation of its nested apply metafunction.

Expression requirements

In the following table and subsequent specifications, f is a Metafunction Class.

Expression Type Complexity
f::apply::type Any type Unspecified.
f::apply<>::type Any type Unspecified.
f::apply<a1,...an>::type Any type Unspecified.

Expression semantics

typedef f::apply::type x;
Precondition:f is a nullary Metafunction Class; f::apply::type is a type-name.
Semantics:x is the result of the metafunction class invocation.
typedef f::apply<>::type x;
Precondition:f is a nullary Metafunction Class; f::apply<>::type is a type-name.
Semantics:x is the result of the metafunction class invocation.
typedef f::apply<a1,...an>::type x;
Precondition:f is an n-ary metafunction class; apply is a Metafunction.
Semantics:x is the result of the metafunction class invocation with the actual arguments a1,... an.

Models

See also

Metafunctions, Metafunction, Lambda Expression, invocation, apply_wrap, bind, quote