IronLanguages / IronLanguages/ironpython3

NullReferenceException while creating IronPython engine in referenced project

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C#
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Description

Description

When calling

var eng = IronPython.Hosting.Python.CreateEngine();

from inside a referenced project, a

NullReferenceException
   at IronPython.Runtime.Importer.ImportReflected(CodeContext context, String name)

will get thrown.

Continue during debugging in VS does work, though, and will create a usable engine nevertheless.

Steps to Reproduce

Create a Windows Forms Application and a library project.
Install the IronPython NuGet package in the library project and use the code above to create an engine from within the referenced assembly.

Running the code from within the library throws the NullReferenceException in Importer.ImportReflected().

Trying the exact same steps directly in the main application works without problems.

Version Information
  • .NET 4.8
  • Windows Forms application/library
  • IronPython 3.4.1 installed via NuGet

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the Windows Forms application and referenced library setup on .NET 4.8 with IronPython 3.4.1, calling Python.CreateEngine() from the library. Investigate the NullReferenceException at IronPython.Runtime.Importer.ImportReflected and compare it with the working call from the main application. Done means the library call creates a usable engine without requiring debugger continuation.

Written by the indexing model from the issue text.

Assessment

Tech stack
csharp, python
Domain
backend
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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