How to get a Python Style Traceback in Ironpython3?

Question

I have a script that can run a python string but if there is an error I want to be able to get a string formatted like a standard python error. I'm using IronPython 3.4

This is the C# code I currently have:

using UnityEngine;
using IronPython.Hosting;
using System.IO;

public class test : MonoBehaviour
{
void Start()
{
var memoryStream = new MemoryStream();
var engine = Python.CreateEngine();
engine.Runtime.IO.SetOutput(memoryStream, System.Text.Encoding.Default);
var scope = engine.CreateScope();

        string code = @"print(var)";
        try {
            var source = engine.CreateScriptSourceFromString(code);
            source.Execute(scope);
        }
        catch(System.Exception e)
        {
            Debug.Log(e);
        }
    
        Debug.Log(System.Text.Encoding.ASCII.GetString(memoryStream.ToArray()));
    }

}

What I want to be output is something like this:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'var' is not defined

I tried using engine.Runtime.IO.SetErrorOutput but that didn't do anything.

Answer 1

After more digging I found pythonContext.FormatException(e) which gave me exactly what I needed. To get the Python context I used PythonContext context = (PythonContext)Microsoft.Scripting.Hosting.Providers.HostingHelpers.GetLanguageContext(engine);

So in the end I got this code:

using UnityEngine;
using IronPython.Hosting;
using IronPython.Runtime;
using System.IO;

public class test : MonoBehaviour
{
    void Start()
    {
        var memoryStream = new MemoryStream();
        var engine = Python.CreateEngine();
        PythonContext context = (PythonContext)Microsoft.Scripting.Hosting.Providers.HostingHelpers.GetLanguageContext(engine);
        engine.Runtime.IO.SetErrorOutput(memoryStream, System.Text.Encoding.Default);
        var scope = engine.CreateScope();

        string code = @"print(var)";
        try {
            var source = engine.CreateScriptSourceFromString(code);
            source.Execute(scope);
        }
        catch(System.Exception e)
        {
            Debug.Log(context.FormatException(e));
        }

        Debug.Log(System.Text.Encoding.ASCII.GetString(memoryStream.ToArray()));
    }

}