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compose()
[Adaptors]

Collaboration diagram for compose():

sigc::compose() combines two or three arbitrary functors. More...

Classes
struct	sigc::compose1_functor<T_setter, T_getter>
	Adaptor that combines two functors. More...
struct	sigc::compose2_functor<T_setter, T_getter1, T_getter2>
	Adaptor that combines three functors. More...
Functions
template<class T_action, class T_setter, class T_getter>
void	sigc::visit_each (const T_action& _A_action, const compose1_functor<T_setter, T_getter>& _A_target)
	Performs a functor on each of the targets of a functor.
template<class T_action, class T_setter, class T_getter1, class T_getter2>
void	sigc::visit_each (const T_action& _A_action, const compose2_functor<T_setter, T_getter1, T_getter2>& _A_target)
	Performs a functor on each of the targets of a functor.
template<class T_setter, class T_getter>
compose1_functor <T_setter, T_getter>	sigc::compose (const T_setter& _A_setter, const T_getter& _A_getter)
	Creates an adaptor of type sigc::compose1_functor which combines two functors.
template<class T_setter, class T_getter1, class T_getter2>
compose2_functor < T_setter, T_getter1, T_getter2 >	sigc::compose (const T_setter& _A_setter, const T_getter1& _A_getter1, const T_getter2& _A_getter2)
	Creates an adaptor of type sigc::compose2_functor which combines three functors.

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Detailed Description

sigc::compose() combines two or three arbitrary functors.

On invokation parameters are passed on to one or two getter functor(s). The return value(s) are then passed on to the setter function.

Examples:

   float square_root(float a)  { return sqrtf(a); }
   float sum(float a, float b) { return a+b; }
   std::cout << sigc::compose(&square_root, &sum)(9, 16); // calls square_root(sum(3,6))
   std::cout << sigc::compose(&sum, &square_root, &square_root)(9); // calls sum(square_root(9), square_root(9))

The functor sigc::compose() returns can be passed into sigc::signal::connect() directly.

Example:

   sigc::signal<float,float,float> some_signal;
   some_signal.connect(sigc::compose(&square_root, &sum));

For a more powerful version of this functionality see the lambda library adaptor sigc::group() which can bind, hide and reorder arguments arbitrarily. Although sigc::group() is more flexible, sigc::bind() provides a means of binding parameters when then total number of parameters called is variable.

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Function Documentation

template <class T_setter, class T_getter1, class T_getter2>

compose2_functor<T_setter, T_getter1, T_getter2> sigc::compose	(	const T_setter &	_A_setter,
		const T_getter1 &	_A_getter1,
		const T_getter2 &	_A_getter2
	)			[inline]

Creates an adaptor of type sigc::compose2_functor which combines three functors.

Parameters:

	_A_setter	Functor that receives the return values of the invokation of _A_getter1 and _A_getter2.
	_A_getter1	Functor to invoke from operator()().
	_A_getter2	Functor to invoke from operator()().

Returns:

Adaptor that executes _A_setter with the values return from invokation of _A_getter1 and _A_getter2.

template <class T_setter, class T_getter>

compose1_functor<T_setter, T_getter> sigc::compose	(	const T_setter &	_A_setter,
		const T_getter &	_A_getter
	)			[inline]

Creates an adaptor of type sigc::compose1_functor which combines two functors.

Parameters:

	_A_setter	Functor that receives the return value of the invokation of _A_getter.
	_A_getter	Functor to invoke from operator()().

Returns:

Adaptor that executes _A_setter with the value returned from invokation of _A_getter.

template <class T_action, class T_setter, class T_getter1, class T_getter2>

void sigc::visit_each	(	const T_action &	_A_action,
		const compose2_functor< T_setter, T_getter1, T_getter2 > &	_A_target
	)			[inline]

Performs a functor on each of the targets of a functor.

The function overload for sigc::compose2_functor performs a functor on the functors stored in the sigc::compose2_functor object.

template <class T_action, class T_setter, class T_getter>

void sigc::visit_each	(	const T_action &	_A_action,
		const compose1_functor< T_setter, T_getter > &	_A_target
	)			[inline]

Performs a functor on each of the targets of a functor.

The function overload for sigc::compose1_functor performs a functor on the functors stored in the sigc::compose1_functor object.

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