C#/Python: Creating Python Wrapper for C# Class by Using Python for .NET

Interoperability is just amazing concept. Sometimes, instead re-inventing the wheel again for a new language, it might be easier to recycle the old stuff. Creating Python wrapper for C++ program was presented in previous post. This post will present simple steps for creating Python wrapper for a simple C#.NET class.

Python for .NET

Python for .NET is a package, that gives Python programmers nearly seamless integration with .NET Common Language Runtime. With this package, you can script .NET applications or build entire applications in Python, using .NET services and components written in any language that targets the CLR (C#, VB.NET, F#, C++/CLI). Download package from here.

Create C# class

In Visual Studio, create a new C# class library project under the namespace CsLibrary. Create C# class Functions into this class project. The content of this class is presented below.

using System;

namespace CsLibrary
{
    // C# class
    public class Functions
    {

        public double Add(double a, double b) {
            return a + b;
        }

        public double Subtract(double a, double b) {
            return a - b;
        }

        public double Multiply(double a, double b) {
            return a * b;
        }

        public double Divide(double a, double b) {
            return a / b;
        }

    }
}

Create wrapper for C# class

In order to access this class from Python, we need to have wrapper class, which inherits from DynamicObject. Add the following new class to existing solution. Effectively, this class is just object adapter, which delegates function calls to our previous C# class.

using System;
using System.Dynamic;

namespace CsLibrary {

    public class PyWrapper : DynamicObject {

        // wrapped C# class
        private Functions functions;

        // ctor
        public PyWrapper() {
            functions = new Functions();
        }        
        
        public double Add(double a, double b) {
            return functions.Add(a, b);
        }

        public double Subtract(double a, double b) {
            return functions.Subtract(a, b);
        }

        public double Multiply(double a, double b) {
            return functions.Multiply(a, b);
        }

        public double Divide(double a, double b) {
            return functions.Divide(a, b);
        }
    }
}

Use wrapper class in Python

The following example program is using C# class wrapper (CsLibrary.dll) in Python.

import clr
clr.AddReference(r'..\CsLibrary\bin\Release\CsLibrary.dll')
from CsLibrary import PyWrapper
wrapper = PyWrapper()

x = 1.23
y = 2.34

print(wrapper.Add(x, y))
print(wrapper.Subtract(x, y))
print(wrapper.Multiply(x, y))
print(wrapper.Divide(x, y))

# 3.57
# -1.1099999999999999
# 2.8781999999999996
# 0.5256410256410257

That's it. The files can be downloaded from my GitHub page. Thanks for reading my blog.
-Mike