The C++ Standard Library Extensions A Tutorial and Reference

Chapter 7. The mem_fn Function Template

The conditionings associated with a particular class …produce habitus, structured structures predisposed to function as structuring structures ….

— The Logic of PracticePIERRE BOURDIEU, TRANSLATED BY RICHARD NICE

template <class Ret, class Ty>  unspecified mem_fn(Ret Ty::*pm);

The function template returns a simple call wrapper cw, with a weak result type (see Section 6.2), such that the expression cw(a1, a2, …, aN) is equivalent to INVOKE (pm, a1, a2, …, aN) (see Section 6.2).

The returned call wrapper is derived from std::unary_function<cv Ty*, Ret>—hence defining the nested type result_type as a synonym for Ret and the nested type argument_type as a synonym for cv Ty*— only if the type Ty is a pointer ...