René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Crash when using nested classes with inheritance, which are instantiated from C#","articleBody":"### Environment\r\n\r\n-   Pythonnet version: 2.5.1\r\n-   Python version: Python 3.9.2\r\n-   Operating System: MacOS\r\n-   .NET Runtime: 5.0.200\r\n\r\n### Details\r\n\r\n-   Describe what you were trying to get done.\r\n\r\nI am accessing a member of a nested C# class which inherits from the enclosing class.\r\n\r\nWhen doing this, the Pythonnet runtime crashes!\r\n\r\nHere is a minimal example:\r\n\r\n```cs\r\nnamespace pythonnet_testing {\r\n\r\n  public class Bar {\r\n    public class Hej : Bar {\r\n    }\r\n  }\r\n\r\n  public class Foo {\r\n    public Bar Bar;\r\n\r\n    public static Foo Create() {\r\n      Foo f = new();\r\n      f.Bar = new Bar.Hej();\r\n      return f;\r\n    }\r\n  }\r\n\r\n  class Program {\r\n    static void Main(string[] args) {\r\n\r\n      var pyCode = @\"\r\nimport pythonnet_testing\r\nf = pythonnet_testing.Foo.Create()\r\nprint('Trying to access member of nested subclass')\r\nprint(f'Bar: {f.Bar}')\r\n      \";\r\n\r\n      PythonEngine.Initialize();\r\n\r\n      using (Py.GIL()) {\r\n        PythonEngine.Exec(pyCode);\r\n      }\r\n\r\n      Console.WriteLine(\"EXIT\");\r\n    }\r\n  }\r\n}\r\n```\r\n\r\nThis seem to be specifically for nested classes, where the object instance is created from the C# environment, and the class has not been explicitly referenced/used from python.\r\n\r\nI have found a way to prevent the crash, by first explicitly using the nested class in the python code.\r\n\r\nEg instead of this:\r\n\r\n```py\r\nimport pythonnet_testing\r\nf = pythonnet_testing.Foo.Create()\r\nprint('Trying to access member of nested subclass')\r\nprint(f'Bar: {f.Bar}')\r\n```\r\n\r\nI insert a reference to the nested `Bar.Hej` class\r\n\r\n```py\r\nimport pythonnet_testing\r\nf = pythonnet_testing.Foo.Create()\r\nprint('Trying to access member of nested subclass')\r\n_ = pythonnet_testing.Bar.Hej # Explicitly referencing the nested class\r\nprint(f'Bar: {f.Bar}')\r\n```\r\n\r\nIf I do this, then the Pythonnet runtime no longer crashes. It is even enough to reference the enclosing baseclass `Bar`\r\n\r\n```py\r\n_ = pythonnet_testing.Bar # Explicitly referencing the enclosing class\r\nprint(f'Bar: {f.Bar}')\r\n```\r\n\r\nWhen I do this, the python code executes properly:\r\n```\r\nTrying to access member of nested subclass\r\nBar: pythonnet_testing.Bar+Hej\r\n```","author":{"url":"https://github.com/koliyo","@type":"Person","name":"koliyo"},"datePublished":"2021-03-10T07:51:49.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":3},"url":"https://github.com/1414/pythonnet/issues/1414"}