What is the .Net equivalent of Java's Dynamic Proxies?

Question

In java it's possible to dynamically implement an interface using a dynamic proxy, something like this:

public static <T> T createProxy(InvocationHandler invocationHandler, Class<T> anInterface) {
    if (!anInterface.isInterface()) {
        throw new IllegalArgumentException("Supplied interface must be an interface!");
    }
    return (T) Proxy.newProxyInstance(anInterface.getClassLoader(), new Class[]{anInterface}, invocationHandler);
}

Is there an equivalent in .Net?

Answer 1

There is no direct equivalent but see How to do Dynamic Proxies in C# for some workarounds:

Background: A dynamic proxy dynamically generates a class at runtime that conforms to a particular interface, proxying all invocations to a single 'generic' method.

Earlier, Stellsmi asked if it's possible to do this in .NET (it's a standard part of Java). Seeing as it's the second time I've talked about it in as many days, I reckon it's worth blogging...

Answer 2

There are several libraries that implement this in .NET. Here's a list of them, with a benchmark.

Answer 3

Yes. You derive from the abstract RealProxy class.

Answer 4

Take a look at PoshSharp as well (AOP framework for .NET) - it can do similar things, but in compile time. Probably you'd prefer the approach it supports.

Answer 5

The most widely used one is the Castle Project's Dynamic Proxy, which is also used by several (or at least 1) mocking frameworks. Keep in mind that methods (and sugared-up methods like properties) are not virtual by default in dotnet, so that can create some headaches if you weren't anticipating it in your class design.