Signals

A simple multi-threaded message passing system. More...

Classes
class	cpp::AsyncSink
	Implements an asynchronous signal sink suited for communication between different threads. More...
class	cpp::SignalEmitter
	Class that can send and receive signals from other emitters. More...
class	cpp::SignalSink
	Interface to the signals sink API. More...
class	cpp::SyncSink
	Implements a direct connection to the destination function. More...

Functions
template<typename Class >
auto	cpp::emit (const Class &object)
	Emits a const signal from the given const SignalEmitter. More...
template<typename Class >
auto	cpp::emit (Class &object)
	Emits a signal from the given SignalEmitter. More...

Detailed Description

A simple multi-threaded message passing system.

The siplasplas-signals module implements a simple message passing system where objects raise signals in the form of member functions which cause connected functions to be invoked.

Despite other message passing systems, siplasplas does not have a class representation for the connection concept, but represents connections as associations between SignalEmitters and SignalSinks. A signal sink is the destination of a raised signal, and keeps track of the callee function (And or callee object).

siplasplas-signals is not specifically designed with performance in mind but with simplicity of user code:

• No special tagging is needed: siplasplas represents connections as associations between an emitter object, a class member function (the signal), and a destination function (A free function, a lambda, callee object + member function, etc). *"Signals"* are just an abstraction represented by member functions with an empty body.
• Type erased connections: Connections are type erased so there are two fixed cpp::SignalSink and cpp::SignalEmitter class hierarchies (As oppossed to Sink templates). This means the user just only has to inherit from cpp::SignalEmitter to raise and emmit signals, and SignalSink to implement a new category of Sink.
• Explicit usage: There are no implicit polling loops, the user is in charge of polling non-direct connections (Such as async connections between threads) for incoming signals.

Function Documentation

template<typename Class >

auto cpp::emit

(

const Class &

object

)

Emits a const signal from the given const SignalEmitter.

This function provides a succint way to emit signals from objects by providing a fake object to pick the required signal. Overloaded signals are supported.

Template Parameters

Class

Type of the signal emitter. Static reflection metadata of this class should be available in the translation unit the emit() function is invoked.

Parameters

object

Object which emits the signal

Returns

A cpp::static_reflection::Class<Class>::FakeObject instance which invokes the selected signal.

class Foo : public cpp::SignalEmitter
{
public:
    void signal();
    void signal(int i);
};

Foo foo;

cpp::emit(foo).signal(); // Emits &Foo::signal from foo
cpp::emit(foo).signal(42); // Emits &Foo::signal(int) with param '42' from Foo

Examples:

signals/signals.cpp.

template<typename Class >

auto cpp::emit

(

Class &

object

)

Emits a signal from the given SignalEmitter.

This function provides a succint way to emit signals from objects by providing a fake object to pick the required signal. Overloaded signals are supported.

Template Parameters

Class

Type of the signal emitter. Static reflection metadata of this class should be available in the translation unit the emit() function is invoked.

Parameters

object

Object which emits the signal

Returns

A cpp::static_reflection::Class<Class>::FakeObject instance which invokes the selected signal.

class Foo : public cpp::SignalEmitter
{
public:
    void signal();
    void signal(int i);
};

Foo foo;

cpp::emit(foo).signal(); // Emits &Foo::signal from foo
cpp::emit(foo).signal(42); // Emits &Foo::signal(int) with param '42' from Foo