Note to Self 8 - IronPython2, Hosting, DLR

• The latest DLR code and documentation can be found at www.codeplex.com/dlr
• For the examples below, here is the Python script I'm using
  

class Person(object):
    def __init__(self, name, phone):
        self.name = name
        self.phone = phone
    def TalkToCSharp(self):
        val = {"name":self.name, "phone":self.phone}
        return val

 

def GetPerson():
    person = Person("darrell", "555-4321")
    return person.TalkToCSharp()


def GetPersonWithParams(name, phone):
    person = Person(name, phone)
    return person.TalkToCSharp()

theNumberFive = 5
myPerson = GetPerson()

• Simplest thing you can do is execute a Python script.
  
  

static void ExecutePythonScript(string path)
{
    ScriptRuntime runtime = Python.CreateRuntime();
    runtime.ExecuteFile(path);
}

• Sometimes you need to get a variable after a script has run.
  

static void GetDoubleVariable(string path)
{
    ScriptRuntime runtime = Python.CreateRuntime();
    ScriptScope scope = runtime.ExecuteFile(path);
    object x = scope.GetVariable("theNumberFive");
    Console.WriteLine(x);
}

• What happens if you're trying to return a custom class defined in the script? The easiest - and IMHO the best - way to go about this is to convert the object to a dictionary before passing it to your C# code.
  

static void GetInstanceCustomClass(string path)
{
    ScriptRuntime runtime = Python.CreateRuntime();
    ScriptScope scope = runtime.ExecuteFile(path);
    PythonDictionary dictionary =
        scope.GetVariable("myPerson")
        as PythonDictionary;
    foreach (var property in dictionary)
        Console.WriteLine(property.Key +
            " == " + property.Value);
}

• Getting properties is definitely useful, but you'll probably want to call a function.
  

static void CallingAFunction(string path)
{
    ScriptRuntime runtime = Python.CreateRuntime();
    ScriptScope scope = runtime.ExecuteFile(path);
    ObjectOperations op =
        scope.Engine.CreateOperations();
    ObjectHandle handle =
        scope.GetVariableHandle("GetPerson");
    var x = op.Call(handle, new object[0]);
    PythonDictionary dictionary =
        x.Unwrap() as PythonDictionary;
    foreach (var property in dictionary)
        Console.WriteLine(property.Key +
            " == " + property.Value);
}

• Here's an example of passing parameters to a Python function.
  

static void CallingAFunctionWithParameters(string path)
{
    ScriptRuntime runtime = Python.CreateRuntime();
    ScriptScope scope = runtime.ExecuteFile(path);
    ObjectOperations op =
        scope.Engine.CreateOperations();
    ObjectHandle handle =
        scope.GetVariableHandle("GetPersonWithParams");
    var x = op.Call(handle, "Larry", "555-1234");
    PythonDictionary dictionary =
        x.Unwrap() as PythonDictionary;
    foreach (var property in dictionary)
        Console.WriteLine(property.Key +
            " == " + property.Value);
}