CODEWITHSUNDEEP
c#reflectiondelegates
jameszhao00
jameszhao00

Reputation: 7301

Delegate.CreateDelegate without prototype

Right now, I have to do this

private delegate void set(int obj); //declare the prototype

...
Delegate delegate1 = Delegate.CreateDelegate(typeof(set), new testObject(), props[0].GetSetMethod());

((set)delegate1)(1);

Is there a way to CreateDelegate without that prototype and call it with any parameter? GetSetMethod() returns a very specific MethodInfo that takes a specific type as an argument.

Thanks

Upvotes: 2

Views: 2130

Answers (1)

Marc Gravell
Marc Gravell

Reputation: 1063005

In .NET 3.5 you can use Expression.GetActionType:

    Type setterType = Expression.GetActionType(props[0].PropertyType);
    Delegate delegate1 = Delegate.CreateDelegate(setterType,
        new testObject(), props[0].GetSetMethod()
    );

Or if you want an open delegate (i.e. to any testObject instance, not bound to the new one):

    Type setterType = Expression.GetActionType(
        props[0].DeclaringType, props[0].PropertyType);
    Delegate delegate1 = Delegate.CreateDelegate(setterType,
        null, props[0].GetSetMethod()
    );

However; note that you'd have to use these delegates via DynamicInvoke, which is much slower than using a fully typed delegate via Invoke.

Another option (for this scenario) is to bind to a delegate that takes object, and use casting inside the delegate - via perhaps some fancy generics, a compiled Expression, or custom IL.

Upvotes: 3

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