Embedding IronPython – Reflective Code

In my current programming project, I’ve embedded IronPython in a C# program. I thought I would share the basics of embedding a scripting engine. I imagine the process would be the same for any language that uses the DLR (Dynamic Language Runtime), like IronRuby. Here is a sample using IronPython 2.0 Beta 5.

using System;

using IronPython.Hosting;

using Microsoft.Scripting;

using Microsoft.Scripting.Hosting;

public class Program

    // Delegate matching the signature of the factorial function

    delegate int FactorialDelegate(int n);

    static void Main(string[] args)

        // Our factorial function

        string[] lines = {"def factorial(n):",

                          "  for i in range(1, n):",

                          "    n = n * i",

                          "  return n"};

        string code = String.Join("\r", lines);

        // Instantiate the IronPython environment

        ScriptEngine engine = Python.CreateEngine();

        // Create a scope/module to work in

        ScriptScope scope = engine.CreateScope();

        // A little preparation

        ScriptSource source = engine.CreateScriptSourceFromString(code, SourceCodeKind.Statements);

        // Compile the code

        CompiledCode compiled = source.Compile();

        // Execute the code in the scope

        compiled.Execute(scope);

        //Now the factorial function exists in the IronPython environment. Let's use it.

        // Set x = 5

        scope.SetVariable("x", 5);

        // print factorial(x)

        ScriptSource print = engine.CreateScriptSourceFromString("print factorial(x)", SourceCodeKind.SingleStatement);

        print.Execute(scope);       //outputs 120

        // Get the result from IronPython

        int result1 = scope.Execute<int>("factorial(6)");

        Console.WriteLine(result1); //outputs 720

        // We can also call the function directly from C#

        FactorialDelegate factorial = scope.GetVariable<FactorialDelegate>("factorial");

        int result2 = factorial(7);

        Console.WriteLine(result2); //outputs 5040

        Console.Read();