simco50/cppdelegates

Single C++ header/source file that implements modern delegates

C++ Delegates

The point of this repository is just to experiment and create delegates in C++. These are not standard in C++ but are a great way for communication and it's widely known in other programming languages like C#. Unreal Engine is worth noting as it has its own implementation of Delegates in C++ too.

Classes

• Delegate<RetVal, Args>
• MulticastDelegate<Args>

Features

• Support for:
  • Static/Global methods
  • Member functions
  • Lambda's
  • std::shared_ptr
• Delegate object is allocated inline if it is under 32 bytes
• Add payload to delegate during bind-time
• Move operations enable optimization

Example Usage

Delegate

Delegate<int, float> del;
del.BindLambda([](float a, int payload)
{
	std::cout << "Lambda delegate parameter: " << a << std::endl;
	std::cout << "Lambda delegate payload: " << payload << std::endl;
	return 10;
}, 50);
std::cout << "Lambda delegate return value: " << del.Execute(20) << std::endl;

Output:
Lambda delegate parameter: 20
Lambda delegate payload: 50
Lambda delegate return value: 10

MulticastDelegate

struct Foo
{
	void Bar(float a, int payload)
	{
		std::cout << "Raw delegate parameter: " << a << std::endl;
		std::cout << "Raw delegate payload: " << payload << std::endl;
	}
};
MulticastDelegate<float> del;
del.AddLambda([](float a, int payload)
{
	std::cout << "Lambda delegate parameter: " << a << std::endl;
	std::cout << "Lambda delegate payload: " << payload << std::endl;
}, 90);

Foo foo;
del.AddRaw(&foo, &Foo::Bar, 10);
del.Broadcast(20);

Output:
Lambda delegate parameter: 20
Lambda delegate payload: 90
Raw delegate parameter: 20
Raw delegate payload: 10

cppdelegates's Issues

Have you done a performance comparison and which c++ std version it need?

String arguments not completely working with `Broadcast(...)`

When I use a multicast delegate in 'raw' mode and one of the passed arguments to broadcast is a std::string only the first instance of the collection gets the value, others get an empty string:

TestClass t1 = TestClass();
TestClass t2 = TestClass();
MulticastDelegate<std::string> del2;

del2.AddRaw(&t1, &TestClass::DoSomething);
del2.AddRaw(&t2, &TestClass::DoSomething);

del2.Broadcast("Test");

Output:

TestClass Did Something. Argument: "Test"
TestClass Did Something. Argument: ""