KDBindings::Signal< Args > Class Template Reference

A Signal provides a mechanism for communication between objects. More...

#include <signal.h>

Public Member Functions
	Signal ()=default
	Signal (const Signal &)=delete
	Signal (Signal &&other) noexcept=default
	~Signal ()
bool	blockConnection (const ConnectionHandle &handle, bool blocked)
template<typename Func , typename... FuncArgs, typename = std::enable_if_t<std::disjunction_v<std::negation<std::is_convertible<Func, std::function<void(Args...)>>>, std::integral_constant<bool, sizeof...(FuncArgs) >>>>
ConnectionHandle	connect (Func &&slot, FuncArgs &&...args)
ConnectionHandle	connect (std::function< void(Args...)> const &slot)
void	disconnect (const ConnectionHandle &handle)
void	disconnectAll ()
void	emit (Args... p) const
bool	isConnectionBlocked (const ConnectionHandle &handle) const
Signal &	operator= (Signal &&other) noexcept=default
Signal &	operator= (Signal const &other)=delete

Detailed Description

template<typename... Args>
class KDBindings::Signal< Args >

A Signal provides a mechanism for communication between objects.

KDBindings::Signal recreates the Qt's Signals & Slots mechanism in pure C++17. A Signal can be used to notify any number of slots that a certain event has occurred.

The slot can be almost any callable object, including member functions and lambdas.

This connection happens in a type-safe manner, as a slot can only be connected to a Signal when the arguments of the slot match the values the Signal emits.

The Args type parameter pack describe which value types the Signal will emit.

Examples:

• 01-simple-connection/main.cpp
• 02-signal-member/main.cpp
• 03-member-arguments/main.cpp
• 07-advanced-connections/main.cpp

Definition at line 217 of file signal.h.

Constructor & Destructor Documentation

Signal() [1/3]

template<typename... Args>

KDBindings::Signal< Args >::Signal ( )

default

Signals are default constructible

Signal() [2/3]

template<typename... Args>

KDBindings::Signal< Args >::Signal ( const Signal< Args > &  )

delete

Signals cannot be copied.

Signal() [3/3]

template<typename... Args>

KDBindings::Signal< Args >::Signal ( Signal< Args > &&  other )

defaultnoexcept

Signals can be moved

~Signal()

template<typename... Args>

KDBindings::Signal< Args >::~Signal ( )

inline

A signal disconnects all slots when it is destructed

Therefore, all active ConnectionHandles that belonged to this Signal will no longer be active (i.e. ConnectionHandle::isActive will return false).

Definition at line 334 of file signal.h.

References KDBindings::Signal< Args >::disconnectAll().

Member Function Documentation

blockConnection()

template<typename... Args>

bool KDBindings::Signal< Args >::blockConnection ( const ConnectionHandle &  handle, bool  blocked  )

inline

Sets the block state of the connection. If a connection is blocked, emitting the Signal will no longer call this connections slot, until the connection is unblocked.

ConnectionHandle::block can be used as an alternative.

To temporarily block a connection, consider using an instance of ConnectionBlocker, which offers a RAII-style implementation that makes sure the connection is always returned to its original state.

Parameters

blocked	Whether the connection should be blocked from now on.
handle	The ConnectionHandle to block.

Returns

Whether the connection was previously blocked.

Exceptions

std::out_of_range

- If the ConnectionHandle does not belong to this Signal (i.e. ConnectionHandle::belongsTo returns false).

Definition at line 450 of file signal.h.

References KDBindings::ConnectionHandle::belongsTo().

connect() [1/2]

template<typename... Args>

template<typename Func , typename... FuncArgs, typename = std::enable_if_t<std::disjunction_v<std::negation<std::is_convertible<Func, std::function<void(Args...)>>>, std::integral_constant<bool, sizeof...(FuncArgs) >>>>

ConnectionHandle KDBindings::Signal< Args >::connect ( Func &&  slot, FuncArgs &&...  args  )

inline

A template overload of Signal::connect that makes it easier to connect arbitrary functions to this Signal. It connects a function to this Signal, binds any provided arguments to that function and discards any values emitted by this Signal that aren't needed by the resulting function.

This is especially useful for connecting member functions to signals.

Examples:

Signal<int> signal;
std::vector<int> numbers{ 1, 2, 3 };
bool emitted = false;
 
// disambiguation necessary, as push_back is overloaded.
void (std::vector<int>::*push_back)(const int &) = &std::vector<int>::push_back;
signal.connect(push_back, &numbers);
 
// this slot doesn't require the int argument, so it will be discarded.
signal.connect([&emitted]() { emitted = true; });
 
signal.emit(4); // Will add 4 to the vector and set emitted to true

For more examples see the 07-advanced-connections/main.cpp example.

Returns

An instance of a Signal::ConnectionHandle that refers to this connection. Warning: When connecting a member function you must use the returned ConnectionHandle to disconnect when the object containing the slot goes out of scope!

Definition at line 390 of file signal.h.

References KDBindings::Private::bind_first(), and KDBindings::Signal< Args >::connect().

connect() [2/2]

template<typename... Args>

ConnectionHandle KDBindings::Signal< Args >::connect ( std::function< void(Args...)> const &  slot )

inline

Connects a std::function to the signal.

When emit() is called on the Signal, the functions will be called with the arguments provided to emit().

Returns

An instance of ConnectionHandle, that can be used to disconnect or temporarily block the connection.

Definition at line 348 of file signal.h.

Referenced by KDBindings::Signal< Args >::connect().

disconnect()

template<typename... Args>

void KDBindings::Signal< Args >::disconnect ( const ConnectionHandle &  handle )

inline

Disconnect a previously connected slot.

After the slot was successfully disconnected, the ConnectionHandle will no longer be active. (i.e. ConnectionHandle::isActive will return false).

Exceptions

std::out_of_range

- If the ConnectionHandle does not belong to this Signal (i.e. ConnectionHandle::belongsTo returns false).

Definition at line 405 of file signal.h.

References KDBindings::ConnectionHandle::belongsTo().

disconnectAll()

template<typename... Args>

void KDBindings::Signal< Args >::disconnectAll ( )

inline

Disconnect all previously connected functions.

All currently active ConnectionHandles that belong to this Signal will no longer be active afterwards. (i.e. ConnectionHandle::isActive will return false).

Definition at line 421 of file signal.h.

Referenced by KDBindings::Signal< Args >::~Signal().

emit()

template<typename... Args>

void KDBindings::Signal< Args >::emit ( Args...  p ) const

inline

Emits the Signal, which causes all connected slots to be called, as long as they are not blocked.

The arguments provided to emit will be passed to each slot by copy, therefore consider using (const) references as the Args to the Signal wherever possible.

Note: Slots may disconnect themselves during an emit, however it is undefined whether a slot that is connected during the emit function of the Signal will also be called during this emit, or only at the next emit.

Definition at line 491 of file signal.h.

Referenced by KDBindings::Property< T >::~Property().

isConnectionBlocked()

template<typename... Args>

bool KDBindings::Signal< Args >::isConnectionBlocked ( const ConnectionHandle &  handle ) const

inline

Checks whether the connection is currently blocked.

To change the blocked state of a connection, call blockConnection().

Returns

Whether the connection is currently blocked

Exceptions

std::out_of_range

- If the ConnectionHandle does not belong to this Signal (i.e. ConnectionHandle::belongsTo returns false).

Definition at line 468 of file signal.h.

References KDBindings::ConnectionHandle::belongsTo().

operator=() [1/2]

template<typename... Args>

Signal & KDBindings::Signal< Args >::operator= ( Signal< Args > &&  other )

defaultnoexcept

operator=() [2/2]

template<typename... Args>

Signal & KDBindings::Signal< Args >::operator= ( Signal< Args > const &  other )

delete

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The documentation for this class was generated from the following file:

• signal.h