在C#中实例化python类

Question

我在python中编写了一个类,我希望通过IronPython将其包装到.net程序集中并在C#应用程序中实例化.我已经将类迁移到IronPython,创建了一个库程序集并引用它.现在,我如何实际获得该类的实例？

该类看起来(部分)像这样:

class PokerCard:
    "A card for playing poker, immutable and unique."

    def __init__(self, cardName):

我在C#中编写的测试存根是:

using System;

namespace pokerapp
{
    class Program
    {
        static void Main(string[] args)
        {
            var card = new PokerCard(); // I also tried new PokerCard("Ah")
            Console.WriteLine(card.ToString());
            Console.ReadLine();
        }
    }
}

为了在C#中实例化这个类,我该怎么办？

Answer 1

IronPython类不是 .NET类.它们是IronPython.Runtime.Types.PythonType的实例,它是Python元类.这是因为Python类是动态的,并且支持在运行时添加和删除方法,这是.NET类无法做到的.

要在C#中使用Python类,您需要使用ObjectOperations类.该类允许您在语言本身的语义中操作python类型和实例.例如,它在适当时使用魔术方法,自动将整数提升为long等.您可以通过查看源或使用反射器来了解有关ObjectOperations的更多信息.

这是一个例子.Calculator.py包含一个简单的类:

class Calculator(object):
    def add(self, a, b):
        return a + b

您可以在.NET 4.0 C#代码中使用它,如下所示:

ScriptEngine engine = Python.CreateEngine();
ScriptSource source = engine.CreateScriptSourceFromFile("Calculator.py");
ScriptScope scope = engine.CreateScope();

ObjectOperations op = engine.Operations;

source.Execute(scope); // class object created
object klaz = scope.GetVariable("Calculator"); // get the class object
object instance = op.Call(klaz); // create the instance
object method = op.GetMember(instance, "add"); // get a method
int result = (int)op.Call(method, 4, 5); // call method and get result (9)

您需要引用程序集IronPython.dll,Microsoft.Scripting和Microsoft.Scripting.Core.

C#4使用新的动态类型使这变得更容易.

ScriptEngine engine = Python.CreateEngine();
ScriptSource source = engine.CreateScriptSourceFromFile("Calculator.py");
ScriptScope scope = engine.CreateScope();
source.Execute(scope);

dynamic Calculator = scope.GetVariable("Calculator");
dynamic calc = Calculator();
int result = calc.add(4, 5);

如果您正在使用Visual Studio 2010或更高版本支持NuGet,只需执行此操作即可下载并引用相应的库.

Install-Package IronPython

Answer 2

现在.Net 4.0已经发布并具有动态类型,因此应该更新此示例.使用与m-sharp原始答案相同的python文件:

class Calculator(object):
    def add(self, a, b):
        return a + b

以下是使用.Net 4.0调用它的方法:

string scriptPath = "Calculator.py";
ScriptEngine engine = Python.CreateEngine();
engine.SetSearchPaths(new string[] {"Path to your lib's here. EG:", "C:\\Program Files (x86)\\IronPython 2.7.1\\Lib"});
ScriptSource source = engine.CreateScriptSourceFromFile(scriptPath);
ScriptScope scope = engine.CreateScope();
ObjectOperations op = engine.Operations;
source.Execute(scope);

dynamic Calculator = scope.GetVariable("Calculator");
dynamic calc = Calculator();
return calc.add(x,y);          

同样,您需要添加对IronPython.dll和Microsoft.Scripting的引用.

如您所见,源文件的初始设置和创建是相同的.

但是一旦源成功执行,由于新的"动态"关键字,使用python函数会更容易.