Binder Classes(3)

NAME
Binder Classes -

  Compounds
class binder1st
One of the binder functors.
class binder2nd
One of the binder functors.

  Functions
template<class _Operation, class _Tp> binder1st< _Operation > bind1st (const _Operation &__fn, const _Tp &__x)
One of the binder functors.
template<class _Operation, class _Tp> binder2nd< _Operation > bind2nd (const _Operation &__fn, const _Tp &__x)
One of the binder functors.

Detailed Description

Binders turn functions/functors with two arguments into functors with a single argument, storing an argument to be applied later. For example, an variable B of type binder1st is constructed from a functor f and an argument x. Later, B's operator() is called with a single argument y. The return value is the value of f(x,y). B can be 'called' with various arguments (y1, y2, ...) and will in turn call f(x,y1), f(x,y2), ...

The function bind1st is provided to save some typing. It takes the function and an argument as parameters, and returns an instance of binder1st.

The type binder2nd and its creator function bind2nd do the same thing, but the stored argument is passed as the second parameter instead of the first, e.g., bind2nd(std::minus<float>,1.3) will create a functor whose operator() accepts a floating-point number, subtracts 1.3 from it, and returns the result. (If bind1st had been used, the functor would perform '1.3 - x' instead.

Creator-wrapper functions like bind1st are intended to be used in calling algorithms. Their return values will be temporary objects. (The goal is to not require you to type names like std::binder1st<std::plus<int>> for declaring a variable to hold the return value from bind1st(std::plus<int>,5).

These become more useful when combined with the composition functions.

Function Documentation

  template<class _Operation, class _Tp> binder1st<_Operation> bind1st (const _Operation & __fn, const _Tp & __x) [inline]

One of the binder functors.

Definition at line 376 of file stl_function.h.

  template<class _Operation, class _Tp> binder2nd<_Operation> bind2nd (const _Operation & __fn, const _Tp & __x) [inline]

One of the binder functors.

Definition at line 410 of file stl_function.h.