Getting the argument names along with values in a dynamic method invoke

Question

I am implementing a DynamicObject. In the TryInvokeMethod, in addition to the arguments ( passed in to the method), I also need the names for the parameters if they have been used.

I can see that binder.CallInfo.ArgumentNames does indeed provides the names, but I am not able to associate them with the values. Is there any way to do so, or am I hoping against hope:

public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result)
{
    var names = binder.CallInfo.ArgumentNames;
    foreach (var arg in args)
    {
        arguments.Add(new Argument(arg));
    }
    //I need to associate the names and the args
    result = this;
    return true;
}

So for example if I do a call like:

myDynamicObject.DynamicInvoke("test", something: "test2")

I have test and test2, and also something, but I am not able to get the information that something was the name for test2 and test had no name.

You should assume that the last argument name if any corresponds to last method parameter and so on. — user629926, Nov 13 '12 at 18:53
@user629926 thanks for the pointer. I used that to get the code below. You can still add as answer if you want and I will accept that. — manojlds, Nov 13 '12 at 19:10

score 3 · Accepted Answer · edited May 23 '17 at 11:48

3

I had to use the fact that named arguments occur only after the non-named ones are specified ( thanks to user629926 for pointing to the obvious) and initial code:

var names = binder.CallInfo.ArgumentNames;
var numberOfArguments = binder.CallInfo.ArgumentCount;
var numberOfNames = names.Count;

var allNames = Enumerable.Repeat<string>(null, numberOfArguments - numberOfNames).Concat(names);
arguments.AddRange(allNames.Zip(args, (flag, value) => new Argument(flag, value)));

edited May 23 '17 at 11:48

Community

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answered Nov 13 '12 at 19:05

manojlds

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One option to possibly simplify your code would be to use `var allNames = Enumerable.Repeat(null, numberOfArguments - numberOfNames).Concat(names);`. Then you can just use `Enumerable.Zip` to pair the values and the names, with `null` for unnamed arguments. – Jon Skeet Nov 14 '12 at 15:08
@JonSkeet Ah nice. I did refactor the code above, but this is neater. – manojlds Nov 14 '12 at 17:41

Getting the argument names along with values in a dynamic method invoke

1 Answers1