How to call a method with an enumerated (enum) argument through reflection?

Question

I have to call the following method:

public bool Push(button RemoteButtons)

RemoteButtons is defined this way:

enum RemoteButtons { Play, Pause, Stop }

The Push method belongs to the RemoteControl class. Both the RemoteControl class and the RemoteButton enumeration are located inside an assembly that I need to load at runtime. I'm able to load the assembly and create an instance of RemoteControl this way:

Assembly asm = Assembly.LoadFrom(dllPath);
Type remoteControlType = asm.GetType("RemoteControl");
object remote = Activator.CreateInstance(remoteControlType);

Now, how do I call the Push method knowing that it's sole argument is an enum that I also need to load at runtime?

If I was on C# 4, I would use a dynamic object but I'm on C# 3/.NET 3.5 so it's not available.

Gripper

Even in C#4, I wouldn't use dynamic for this. – Cayla

What do you mean "unknown" enum? – Trinary

I think the OP means: enum RemoteButtons { Play, Pause, Stop } ...if this is correct, the OP needs to make this clear. :) – Cayla

I would have an interface - e.g. IRemoteControl - which exposes bool Push(...) and referenced by the class instantiating via reflection and implemented by RemoteControl. Then you don't have to call the method via reflection. – Cayla

Edited for the sake of clarity. – Gripper

Answer 1

Assuming I have the following structure:

public enum RemoteButtons
{
    Play,
    Pause,
    Stop
}
public class RemoteControl
{
    public bool Push(RemoteButtons button)
    {
        Console.WriteLine(button.ToString());
        return true;
    }
}

Then I can use reflection to get at the values like so:

Assembly asm = Assembly.GetExecutingAssembly();
Type remoteControlType = asm.GetType("WindowsFormsApplication1.RemoteControl");
object remote = Activator.CreateInstance(remoteControlType);

var methodInfo = remoteControlType.GetMethod("Push");
var remoteButtons = methodInfo.GetParameters()[0];

// .Net 4.0    
// var enumVals = remoteButtons.ParameterType.GetEnumValues();

// .Net 3.5
var enumVals = Enum.GetValues(remoteButtons.ParameterType);

methodInfo.Invoke(remote, new object[] { enumVals.GetValue(0) });   //Play
methodInfo.Invoke(remote, new object[] { enumVals.GetValue(1) }); //Pause
methodInfo.Invoke(remote, new object[] { enumVals.GetValue(2) }); //Stop

I am getting the parameter type from the method and then getting the enum values from that type.

Piranha

Unfortunately, it seems like GetEnumValues is only available with .NET 4+. I'm on 3.5. – Gripper

I'm accepting this answer since it provided 95% of what I needed. I just made a small edit so the code will work with .NET 3.5. – Gripper

Answer 2

The follow code can work right!

asm = Assembly.LoadFrom(dllPath);
Type typeClass = asm.GetType("RemoteControl");
obj = System.Activator.CreateInstance(typeClass);
Type[] types = asm.GetTypes();
Type TEnum = types.Where(d => d.Name == "RemoteButtons").FirstOrDefault();
MethodInfo method = typeClass.GetMethod("Push", new Type[] { TEnum});
object[] parameters = new object[] { RemoteButtons.Play };
method.Invoke(obj, parameters);

Pay attention to this code：“Type TEnum = types.Where(d => d.Name == "RemoteButtons").FirstOrDefault();” you must get the Type from the Assembly use this code.

but not Directly use typeof(RemoteButtons) to find the method like this:"MethodInfo method = typeClass.GetMethod("Push", new Type[] { typeof(RemoteButtons) });" This is not Actually the SAME Type .

Episternum