将反射与标准调用混合

Question

Let me preface this by saying that I am completely new to reflection.

I have a Dictionary of string to Func<string, string> . I'd like to add a configuration section that would allow me to define the name of static methods that can be programmatically added into this dictionary.

So basically, I'd have something like this:

public static void DoSomething()
{
    string MethodName = "Namespace.Class.StaticMethodName";

    // Somehow convert MethodName into a Func<string, string> object that can be 
    // passed into the line below

    MyDictionary["blah"] = MethodNameConvertedToAFuncObject;
    MyDictionary["foo"] = ANonReflectiveMethod;

    foreach(KeyValuePair<string, Func<string, string>> item in MyDictionary)
    {
        // Calling method, regardless if it was added via reflection, or not
        Console.WriteLine(item.Value(blah));
    }
}

public static string ANonReflectiveMethod(string AString)
{
    return AString;
}

Is it possible to do this, or do I need everything invoked through reflection?

Answer 1

I think all you're looking for is Delegate.CreateDelegate . You'll need to break the name you've got into a class name and a method name. You can then use Type.GetType() to get the type, then Type.GetMethod() to get the MethodInfo , then use:

var func = (Func<string, string>) Delegate.CreateDelegate(
                            typeof(Func<string, string>), methodInfo);

Once you've created the delegate, you can put it into the dictionary with no problems.

So something like:

static Func<string, string> CreateFunction(string typeAndMethod)
{
    // TODO: *Lots* of validation
    int lastDot = typeAndMethod.LastIndexOf('.');
    string typeName = typeAndMethod.Substring(0, lastDot);
    string methodName = typeAndMethod.Substring(lastDot + 1);
    Type type = Type.GetType(typeName);
    MethodInfo method = type.GetMethod(methodName, new[] { typeof(string) });
    return (Func<string, string>) Delegate.CreateDelegate(
        typeof(Func<string, string>), method);
}

Note that Type.GetType() will only find types in the currently executing assembly or mscorlib unless you actually specify an assembly-qualified name. Just something to consider. You might want to use Assembly.GetType() instead if you already know the assembly you'll be finding the method in.