Signals

Overview

A lightweight "signals and slots" implementation using fast delegates.

When GUI programming in C++, delegates and the signals and slots paradigm can vastly simplify your code. It implements the Observer pattern while avoiding all the boilerplate code. I needed a lightweight and efficient implementation that I could just drop into my projects and use without adding weird macros, inheriting from crazy templates or having external dependencies. I wanted something simpler and more efficient than libsigc++, sigslot, and boost.signals.

So I was overjoyed when I discovered a very novel and efficient implementation of delegates in C++ and I realized I could make use of these to create a signals and slots implementation that would be very non-intrusive.

Features

• Extremely efficient (based on delegates that generate only two lines of ASM code).
• No inheritance required.
• No third-party preprocessor required.
• Works seamlessly with global functions, object methods, virtual methods and static class methods.
• Very portable. This should work on any reasonable C++ compiler.
• Really simple to drop in and use.
• Implemented fully in templates.

Requires

Signals.h does require STL for std::set, although this could probably be replaced with a custom set class fairly easily if you have one on hand. :)

Examples

See Example.cpp for more detailed examples. Here is a very simple one:

// Using Delegate.h

void MyFunc( int x )
{
	printf( "MyFunc( %d )", x );
}


// Using Signal.h

class Button
{	
public:
	Signal2< int, float > updateLabel;

	void Click( void )
	{
		updateLabel( 2, 34.5 );
	}
};

class Label
{
public:
	virtual void Update( int i, float f )
	{
		printf( "Update( %d, %.1f )", i, f );
	}
};

int main()
{
	Delegate1< int > delegate;
	delegate.Bind( & MyFunc );
	delegate( 5 );

	Button myButton;
	Label myLabel1;
	Label myLabel2;
	myButton.updateLabel.Connect( & myLabel1, & Label::Update );
	myButton.updateLabel.Connect( & myLabel2, & Label::Update );
	myButton.Click();

	return 0;
}

Meta

Written by Patrick Hogan

This project includes a modified version of FastDelegates by Don Clugston. Please see Delegates.h for more information on FastDelegates.

Signals.h is released under the MIT License: http://www.opensource.org/licenses/mit-license.php
Delegates.h is released into the public domain by the author and may be used for any purpose.

http://github.com/pbhogan
http://www.gallantgames.com