use enum name in repr

[koubaa]

What does this implement/fix? Explain your changes.

Proposal to fix #2238

Before the changes:

Python 3.11.4 (tags/v3.11.4:d2340ef, Jun  7 2023, 05:45:37) [MSC v.1934 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import clr; import System
>>> System.DayOfWeek.Monday
<System.DayOfWeek object at 0x0000024D5BAC7300>

IronPython (as a reference):

IronPython 2.7.4 (2.7.0.40) on .NET 4.0.30319.42000 (64-bit)
Type "help", "copyright", "credits" or "license" for more information.
>>> import System
>>> System.DayOfWeek.Monday
System.DayOfWeek.Monday

With these changes:

Python 3.11.4 (tags/v3.11.4:d2340ef, Jun  7 2023, 05:45:37) [MSC v.1934 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import clr; import System
>>> System.DayOfWeek.Monday
DayOfWeek.Monday

Checklist

• Make sure to include one or more tests for your change
• If an enhancement PR, please create docs and at best an example
• Ensure you have signed the .NET Foundation CLA
• Add yourself to AUTHORS
• Updated the CHANGELOG

[lostmsu]

Can you please make the format similar to Python's enum.Enum:

>>> from enum import Enum
>>> class Color(Enum):
...   RED = 1
...   GREEN = 2
...
>>> repr(Color.GREEN)
'<Color.GREEN: 2>'

I suggest to use decimal values when enum is a regular enum, and either binary or hexadecimal when it has [Flags].

P.S. Disregard the Mac and ARM failures, they are caused by our test infra.

[koubaa]

@lostmsu Done - but I'm not really that happy with the Flags case. ToString() seems to make some choices about how to represent the value. Do you mean to only show the hex value if its Flags, instead of trying to show both integer and name?

[lostmsu]

@koubaa both of course.

[koubaa]

@lostmsu done.

The switch case isn't so pretty, but I couldn't think of a way to improve it. here's a minimal compiler explorer link with that logic if anyone wants to try and see if they can improve it: https://godbolt.org/z/dYG6sdnKo

[lostmsu]

@koubaa try using Convert.ChangeType

string ConvertFlags(Enum value) {
    Type primitiveType = value.GetType().GetEnumUnderlyingType();
    string format = "X" + (Marshal.SizeOf(primitiveType) * 2).ToString(CultureInfo.InvariantCulture);
    var primitive = (IFormattable)Convert.ChangeType(value, primitiveType);
    return primitive.ToString(format, null);
   
}

string ConvertValue(Enum value) {
    Type primitiveType = value.GetType().GetEnumUnderlyingType();
    return Convert.ChangeType(value, primitiveType).ToString()!;
}