从IronPython调用C＃方法

Question

我正在构建一个可以与IronPython自动化的C＃WebKit Web浏览器，以帮助进行质量保证测试。我将使用IronPython创建测试计划，该计划将运行许多浏览器方法，提供参数并评估结果。

IronPython的大多数文档都说明了如何使用C＃调用IronPython方法，但是我已经弄清楚了如何为方法设置参数，以及如何检索方法的返回值，但不能从同一方法中返回。您将在下面的示例中注意到，我将参数传递给一个方法，该方法依次设置一个类成员变量，然后使用另一个方法检索该值。

谁能建议一个更优雅的图案？

using System;
using System.Windows.Forms;
using IronPython.Hosting;
using Microsoft.Scripting;
using Microsoft.Scripting.Hosting;

namespace PythonScripting.TestApp
{

 public partial class Form1 : Form
 {
   private ScriptEngine m_engine = Python.CreateEngine();
   private ScriptScope m_scope = null;

   //used to call funcs by Python that dont need to return vals
   delegate void VoidFunc(string val);

   public Form1()
   {
      InitializeComponent();
   }

   private void doSomething()
   {
       MessageBox.Show("Something Done", "TestApp Result");
   }

   private string _rslt = "";

   private string getSomething()
   {
      return _rslt;
   }

   private void setSomething(string val)
   {
       _rslt = val;
   }

   private void Form1_Load(object sender, EventArgs e)
   {
       m_scope = m_engine.CreateScope();

       Func<string> PyGetFunction = new Func<string>(getSomething);
       VoidFunc PySetFunction = new VoidFunc(setSomething);

       m_scope.SetVariable("txt", txtBoxTarget);
       m_scope.SetVariable("get_something", PyGetFunction);
       m_scope.SetVariable("set_something", PySetFunction);           
   }

   private void button1_Click(object sender, EventArgs e)
   {
       string code = comboBox1.Text.Trim();
       ScriptSource source = m_engine.CreateScriptSourceFromString(code, SourceCodeKind.SingleStatement);

       try
       {
          source.Execute(m_scope);
          Func<string> result = m_scope.GetVariable<Func<string>>("get_something");

          MessageBox.Show("Result: " + result(), "TestApp Result");
       }
       catch (Exception ue)
       {
           MessageBox.Show("Unrecognized Python Error\n\n" + ue.GetBaseException(), "Python Script Error");
       }
   }  
 }
} 

Answer 1

通常情况下，IronPython只能访问.Net类型的公共类和成员。您应该能够仅将对象设置为作用域中的变量，并从脚本访问该对象上的任何公共成员。但是，您在示例中使用的方法是private如此，因此您无法真正访问它们。如果您希望能够访问它们，则需要以某种方式公开非公共成员，以便您可以操纵它们或使用反射。

您可以尝试的一种模式是添加一个方法，该方法将为您的对象创建一个代理，该代理将具有您要公开的所有方法。然后将该代理对象添加到您的范围，然后使用该代理来调用您的方法。

public partial class MyForm : Form
{
    private readonly ScriptEngine m_engine;
    private readonly ScriptScope m_scope;

    public MyForm()
    {
        InitializeComponent();
        m_engine = Python.CreateEngine();

        dynamic scope = m_scope = m_engine.CreateScope();
        // add this form to the scope
        scope.form = this;
        // add the proxy to the scope
        scope.proxy = CreateProxy();
    }

    // public so accessible from a IronPython script
    public void ShowMessage(string message)
    {
        MessageBox.Show(message);
    }

    // private so not accessible from a IronPython script
    private int MyPrivateFunction()
    {
        MessageBox.Show("Called MyForm.MyPrivateFunction");
        return 42;
    }

    private object CreateProxy()
    {
        // let's expose all methods we want to access from a script
        dynamic proxy = new ExpandoObject();
        proxy.ShowMessage = new Action<string>(ShowMessage);
        proxy.MyPrivateFunction = new Func<int>(MyPrivateFunction);
        return proxy;
    }
}

这样，您就可以执行脚本来通过form变量访问表单，或者通过变量访问代理proxy。作为一种很好的措施，这是您可以轻松地从范围中访问变量和其他对象的方法。

private void DoTests()
{
    // try to call the methods on the form or proxy objects
    var script = @"
form.ShowMessage('called form.ShowMessage')
# formFuncResult = form.MyPrivateFunction() # fail, MyPrivateFunction is not accessible
proxy.ShowMessage('called proxy.ShowMessage')
proxyFuncResult = proxy.MyPrivateFunction() # success, MyPrivateFunction on the proxy is accessible
";
    m_engine.Execute(script, m_scope);

    // access the scope through a dynamic variable
    dynamic scope = m_scope;

    // get the proxyFuncResult variable
    int proxyFuncResult = scope.proxyFuncResult;
    MessageBox.Show("proxyFuncResult variable: " + proxyFuncResult);

    // call the the function on the proxy directly
    int directResult = scope.proxy.MyPrivateFunction();
    MessageBox.Show("result of MyPrivateFunction: " + directResult);
}