https://github.com/farlee2121/staticpropertyenum.generator
List known values for enum-like static member lists (like System.Drawing.Color)
https://github.com/farlee2121/staticpropertyenum.generator
Last synced: 3 months ago
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List known values for enum-like static member lists (like System.Drawing.Color)
- Host: GitHub
- URL: https://github.com/farlee2121/staticpropertyenum.generator
- Owner: farlee2121
- License: unlicense
- Created: 2020-12-28T22:45:40.000Z (over 4 years ago)
- Default Branch: main
- Last Pushed: 2020-12-29T16:21:09.000Z (over 4 years ago)
- Last Synced: 2025-02-02T04:23:55.297Z (4 months ago)
- Language: C#
- Size: 24.4 KB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 3
-
Metadata Files:
- Readme: ReadMe.md
- License: LICENSE
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README
# Static Property Enum Generator
[](https://www.nuget.org/packages/StaticMemberEnum.Generator)
## Why
Enums are great, but often data has a fixed set of known values AND should allows for unknown values.
This can be accomplished with static members on a type. For example [System.Drawing.Color](https://referencesource.microsoft.com/#System.Drawing/commonui/System/Drawing/Color.cs,9103fd761ca562ae).
More examples and exploration is availabe [here](https://spencerfarley.com/2020/08/07/structs-vs-enums/).
This comes with some disadvantages though, like not being able to list the known values without writing boilerplate for every type.
That's what this library solves. It uses the new C# 9 [Source Generators](https://devblogs.microsoft.com/dotnet/introducing-c-source-generators/) to automattically add a `.KnownValues()`
including all static members that have the same type as the containing declaration.
Example. Given
```cs
namespace Some.Namespace{
[StaticMemberEnum]
partial class GolfClubTypes{
private readonly string _id;
public GolfClubTypes(string id) => _id = id;
public static GolfClubTypes Driver = new GolfClubTypes("Driver");
public static GolfClubTypes Iron = new GolfClubTypes("Iron");
public static GolfClubTypes Wedge = new GolfClubTypes("Wedge");
public static GolfClubTypes Hybrid = new GolfClubTypes("Hybrid");
public static GolfClubTypes Wood = new GolfClubTypes("Wood");
}
}
```
The library generates
```cs
namespace Some.Namespace{
partial class GolfClubTypes{
public static IEnumerable KnownValues(){
return new []{Driver, Iron, Wedge, Hybrid, Woood};
}
}
}
```
So that you can call
```cs
IEnumerable clubs = GolfClubTypes.KnownValues();
```
## A few potential gotchas
- The member enum definition has to be partial because source generators behave about the same as adding new sources files.
- This generator currently doesn't work on nested classes. It would require the whole hierarchy of classes to be partial. That seems smelly to me, so I decided not to support it. Let me know in the github issues if you have reasons I should change my mind.
- Classes won't have value-based equality behavior by default, and structs don't define `==` by default. I recommend using records.
- You can use a generator like [Generator.Equals](https://github.com/diegofrata/Generator.Equals) if you still want a class or struct
- Structs should only be used with very small values (under 16 bytes). See [the offical explanation](https://docs.microsoft.com/en-us/dotnet/standard/design-guidelines/choosing-between-class-and-struct)