Using Python Expressions from C# Code

Utilizing the dynamic features of C# and the Dynamic Language Runtime (DLR), among other things, allows C# programs to interoperate with other dynamic languages built on top of the DLR.

For example, python has the ability to chain operators, for example the expression “10 < 15 < 20” returns true: 10 is less than 15 and 15 is less than 20.

To use a chained Python expression from C# code, IronPython can be used.

To get started (in this example a C# console application) first install the IronPython NuGet package . This allows the application to interoperate with Python code.

The following code shows a console application that evaluates a user-entered number “n” against the Python expression “10 < n < 20”:

using IronPython.Hosting; using Microsoft.Scripting; using Microsoft.Scripting.Hosting; using static System.Console; namespace PythonCSharp { class Program { static void Main(string[] args) { const string pythonExpression = "10 < n < 20"; int n; while (true) { WriteLine($"Enter a value for n where {pythonExpression}"); n = int.Parse(ReadLine()); // cast error check omitted ScriptEngine pythonEngine = Python.CreateEngine(); ScriptScope pythonScope = pythonEngine.CreateScope(); // set the value of the Python token "n" in the expression 10 < n < 20 pythonScope.SetVariable("n", n); ScriptSource pythonScriptSource = pythonEngine.CreateScriptSourceFromString(pythonExpression, SourceCodeKind.Expression); // Execute the Python expression and get the return value dynamic dynamicResult = pythonScriptSource.Execute(pythonScope); WriteLine($"{pythonScriptSource.GetCode().Replace("n", n.ToString())} = {dynamicResult}"); WriteLine(); } } } }

Running the console application allows the user to enter a value for “n” and evaluate it against the Python expression as the following image shows:

To learn more about how C# makes dynamic possible, some potential use cases, and more detailed on implementing custom types check out my Dynamic C# Fundamentals Pluralsight course .