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< I_location, T_functor >
	Adaptor that adds a dummy parameter to the wrapped functor. More...

Functions
template <int I_location, typename T_functor >
decltype(auto)	sigc::hide (const T_functor &func)
	Creates an adaptor of type sigc::hide_functor which adds a dummy parameter to the passed functor.
template <typename T_functor >
decltype(auto)	sigc::hide (const T_functor &func)
	Creates an adaptor of type sigc::hide_functor which adds a dummy parameter to the passed functor.
template <typename T_functor >
retype_return_functor< void, T_functor >	sigc::hide_return (const T_functor &functor)
	Creates an adaptor of type sigc::retype_return_functor which drops the return value of the passed functor.

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 argument 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)

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

Example:

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

sigc::hide() can be nested in order to discard multiple arguments.

Example:

// multiple argument hiding ...
// adds two dummy parameters at the back and calls foo(1,2)
sigc::hide(sigc::hide(&foo))(1,2,3,4);

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

Function Documentation

hide() [1/2]

template <int I_location, typename T_functor >

decltype(auto) sigc::hide ( const T_functor &  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

func	Functor that should be wrapped.

Returns

Adaptor that executes func, ignoring the value of the dummy parameter.

hide() [2/2]

template <typename T_functor >

decltype(auto) sigc::hide ( const T_functor &  func )

inline

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

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

Parameters

func	Functor that should be wrapped.

Returns

Adaptor that executes func, ignoring the value of the last parameter.

hide_return()

template <typename T_functor >

retype_return_functor< void, T_functor > sigc::hide_return ( const T_functor &  functor )

inline

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

Parameters

functor

Functor that should be wrapped.

Returns

Adaptor that executes functor dropping its return value.