How can I create an Action delegate from MethodInf

问题:

I want to get an action delegate from a MethodInfo object. Is this possible?

Thank you.

回答1:

Use Delegate.CreateDelegate:

// Static method
Action action = (Action) Delegate.CreateDelegate(typeof(Action), method);

// Instance method (on "target")
Action action = (Action) Delegate.CreateDelegate(typeof(Action), target, method);

For an Action<T> etc, just specify the appropriate delegate type everywhere.

In .NET Core, Delegate.CreateDelegate doesn't exist, but MethodInfo.CreateDelegate does:

// Static method
Action action = (Action) method.CreateDelegate(typeof(Action));

// Instance method (on "target")
Action action = (Action) method.CreateDelegate(typeof(Action), target);

回答2:

This seems to work on top of John's advice too:

public static class GenericDelegateFactory
{
    public static object CreateDelegateByParameter(Type parameterType, object target, MethodInfo method) {

        var createDelegate = typeof(GenericDelegateFactory).GetMethod("CreateDelegate")
            .MakeGenericMethod(parameterType);

        var del = createDelegate.Invoke(null, new object[] { target, method });

        return del;
    }

    public static Action<TEvent> CreateDelegate<TEvent>(object target, MethodInfo method)
    {
        var del = (Action<TEvent>)Delegate.CreateDelegate(typeof(Action<TEvent>), target, method);

        return del;
    }
}