Question

I have embedded an IronPython engine in a C# application. I want to expose some custom commands (methods) to the interpreter. How do I do this?

Currently, I have something like this:

public delegate void MyMethodDel(string printText);

Main(string[] args)
{
    ScriptEngine engine = Python.CreateEngine();
    ScriptScope scope = engine.CreateScope();

    MyMethodDel del = new MyMethodDel(MyPrintMethod);
    scope.SetVariable("myprintcommand", del);

    while(true)
    {
        Console.Write(">>>");
        string line = Console.ReadLine();

        ScriptSource script = engine.CreateScriptSourceFromString(line, SourceCodeKind.SingleStatement);
        CompiledCode code = script.Compile();
        script.Execute(scope);
    }
}

void MyPrintMethod(string text)
{
    Console.WriteLine(text);
}

I can use this like this:

>>>myprintcommand("Hello World!")
Hello World!
>>>

This works fine. I wanted to know, if this is the correct way/best practice to do what I want to achieve?

How can I expose overloads of the same method. For example, if I wanted to expose a method like myprintcommand(string format, object[] args).

With the way I am currently doing it, the key “myprintcommand” can be mapped to only one delegate. Therefore I will have to change the name of the command/method if I want to expose the overloaded “myprintcommand” to the interpreter. Is there any other way to achieve what I want?

Answer 1

You would probably have to write your own logic for that. Eg:

public delegate void MyMethodDel(params object[] args);

void MyPrintMethod(params object[] args)
{
  switch (args.Length)
  {
    case 1:
      Console.WriteLine((string)args[0]);
      break;
    ...
    default:
      throw new InvalidArgumentCountException();
  }
}

This may or may not work; I am not sure how they handle the ‘params’ attribute anymore.