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hide(), hide_return()
[Adaptors]

Collaboration diagram for hide(), hide_return():

sigc::hide() alters an arbitrary functor in that it adds a parameter whose value is ignored on invocation of the returned functor. More...

Classes
struct	sigc::hide_functor<-1, T_functor >
	Adaptor that adds a dummy parameter to the wrapped functor. More...
struct	sigc::hide_functor<0, T_functor>
	Adaptor that adds a dummy parameter to the wrapped functor. More...
struct	sigc::hide_functor<1, T_functor>
	Adaptor that adds a dummy parameter to the wrapped functor. More...
struct	sigc::hide_functor<2, T_functor>
	Adaptor that adds a dummy parameter to the wrapped functor. More...
struct	sigc::hide_functor<3, T_functor>
	Adaptor that adds a dummy parameter to the wrapped functor. More...
struct	sigc::hide_functor<4, T_functor>
	Adaptor that adds a dummy parameter to the wrapped functor. More...
struct	sigc::hide_functor<5, T_functor>
	Adaptor that adds a dummy parameter to the wrapped functor. More...
struct	sigc::hide_functor<6, T_functor>
	Adaptor that adds a dummy parameter to the wrapped functor. More...
Functions
template<class T_action, int I_location, class T_functor>
void	sigc::visit_each (const T_action& _A_action, const hide_functor<I_location, T_functor>& _A_target)
	Performs a functor on each of the targets of a functor.
template<int I_location, class T_functor>
hide_functor < I_location, T_functor >	sigc::hide (const T_functor& _A_func)
	Creates an adaptor of type sigc::hide_functor which adds a dummy parameter to the passed functor.
template<class T_functor>
retype_return_functor <void, T_functor>	sigc::hide_return (const T_functor& _A_functor)
	Creates an adaptor of type sigc::retype_return_functor which drops the return value of the passed functor.

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Detailed Description

sigc::hide() alters an arbitrary functor in that it adds a parameter whose value is ignored on invocation of the returned functor.

Thus you can discard one or more of the arguments of a signal.

You may optionally specify the zero-based position of the parameter to ignore as a template argument. The default is to ignore the last parameter. (A value of -1 adds a parameter at the end so sigc::hide<-1>() gives the same result as sigc::hide().)

The type of the parameter can optionally be specified if not deduced.

Examples:

   void foo(int, int);
   // single argument hiding ...
   sigc::hide(&foo)(1,2,3);     // adds a dummy parameter at the back and calls foo(1,2)
   sigc::hide<-1>(&foo)(1,2,3); // same as sigc::hide(&foo)(1,2,3) (calls foo(1,2))
   sigc::hide<0>(&foo)(1,2,3);  // adds a dummy parameter at the beginning and calls foo(2,3)
   sigc::hide<1>(&foo)(1,2,3);  // adds a dummy parameter in the middle and calls foo(1,3)
   sigc::hide<2>(&foo)(1,2,3);  // adds a dummy parameter at the back and calls foo(1,2)
   // multiple argument hiding ...
   sigc::hide(sigc::hide(&foo))(1,2,3,4); // adds two dummy parameters at the back and calls foo(1,2)

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

Example:

   sigc::signal<void,int> some_signal;
   void foo();
   some_signal.connect(sigc::hide(&foo));

sigc::hide_return() alters an arbitrary functor by dropping its return value, thus converting it to a void functor.

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::hide() provides a means of hiding parameters when then total number of parameters called is variable.

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Function Documentation

template <int I_location, class T_functor>

hide_functor<-1, T_functor > sigc::hide

(

const T_functor &

_A_func

)

[inline]

Creates an adaptor of type sigc::hide_functor which adds a dummy parameter to the passed functor.

The optional template argument I_location specifies the zero-based position of the dummy parameter in the returned functor (-1 stands for the last parameter).

Parameters:

_A_func

Functor that should be wrapped.

Returns:

Adaptor that executes _A_func ignoring the value of the dummy parameter.

This overload adds a dummy parameter at the back of the functor's parameter list.

Parameters:

_A_func

Functor that should be wrapped.

Returns:

Adaptor that executes _A_func ignoring the value of the last parameter.

template <class T_functor>

retype_return_functor<void, T_functor> sigc::hide_return

(

const T_functor &

_A_functor

)

[inline]

Creates an adaptor of type sigc::retype_return_functor which drops the return value of the passed functor.

Parameters:

_A_functor

Functor that should be wrapped.

Returns:

Adaptor that executes _A_functor dropping its return value.

template <class T_action, int I_location, class T_functor>

void sigc::visit_each	(	const T_action &	_A_action,
		const hide_functor< I_location, T_functor > &	_A_target
	)			[inline]

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

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

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