Get Value Of An Enum

Environment

Pythonnet version: latest
Python version: 3.9.4
Operating System: Windows
.NET Runtime:

Details

Describe what you were trying to get done.

I would like to have the ability to extract the value of a .Net Enum via python. One can do that using MyEnum.value__, however it seems logical that you should do it using int(MyEnum).

What commands did you run to trigger this issue? If you can provide a
Minimal, Complete, and Verifiable example
this will help us understand the issue.

import clr

clr.AddReference("System.Windows.Forms")

import System.Windows.Forms as WinForms

enum_value = WinForms.Keys.Control
print(f"{enum_value=}")
print(f"{enum_value.value__=}")

That prints:

enum_value=<System.Windows.Forms.Keys object at 0x000001C053E07580>
enum_value.value__=131072

If there was a crash, please include the traceback here.

No crash.

@lostmsu

This is possible using codecs, though they are /really/ unergonomic so far when using them from Python:

 import Python.Runtime
 Python.Runtime.PyObjectConversions.RegisterEncoder(Python.Runtime.Codecs.EnumPyIntCodec.Instance)
 Python.Runtime.PyObjectConversions.RegisterDecoder(Python.Runtime.Codecs.EnumPyIntCodec.Instance)

The decoder is buggy right now (fix in #1621).

@lostmsu Do you have a proposal for a nice ergonomic Python API for this? Should we enable some encoders/decoders by default unless told otherwise?

I don't think enabling codecs by default is a good idea, unless they are 1:1 exact rountrippable mappings.

As for the more ergonomic Python APIs, somebody more proficient with Python should propose those.

As for the issue at hand, .NET enums should implement __int__ or its C API alternative, nb_int for int(Keys.Control) to work, not a codec.

Isn't that something that we explicitly removed?

If I remember correctly, we removed the code, that converted any enum value to an integer implicitly when passed to Python. You could never previously get raw enum value in Python, it always just saw integers. So the corresponding type never had __int__ implementation.

So if I understand you correctly, we all agree that adding a default __int__ method for all C# enums is a wise idea?

I would have implemented this ability myself, but I have zero knowledge in C#. Let me know if I can help you somehow make this ability happen.

provide `__int__` instance method on .NET enum types to support int(E…

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Get Value Of An Enum #1585

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Get Value Of An Enum #1585

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filmor commented on Nov 23, 2021

lostmsu commented on Nov 23, 2021

lostmsu commented on Nov 23, 2021

filmor commented on Nov 23, 2021

lostmsu commented on Nov 23, 2021

saroad2 commented on Nov 29, 2021

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