enum length

[tothalexlaszlo]

In order to get the length of an enum, source generator can introduce a public constant variable what is faster.

Method	Mean	Error	StdDev	Ratio	Gen 0	Allocated
EnumLength	41.9690 ns	0.2502 ns	0.2218 ns	1.000	0.0076	48 B
EnumLengthExtensions	9.0046 ns	0.0649 ns	0.0607 ns	0.214	0.0076	48 B
EnumLengthProperty	0.0214 ns	0.0046 ns	0.0043 ns	0.001	-	-

[adamradocz]

@andrewlock this is very useful, are you considering to merge this?

[andrewlock]

Thanks @tothalexlaszlo this looks great! Yep @adamradocz definitely going to merge this 🙂 I'm thinking it would probably would sense to merge #13 first given the additional complexity, and rebase this one on top, sound good to you?

[adamradocz]

Yes, sounds perfect. :)

[FroggieFrog]

I thought maybe it is useful to add a documentation comment which clarifies what this property reflects.
Because it is a non distinct count of the names (if I'm correct).
A user could have an enum defined with different names, but same values.

using System;
using System.Linq;

public class Program
{
    public enum Foo
    {
        First = 0,
        Second = 1,
        Third = 1,
    }

    public static void Main()
    {
        var nameCount = Enum.GetNames(typeof(Foo)).Length;
        var valueCount = Enum.GetValues(typeof(Foo)).Length;
        var distinctNameCount = Enum.GetNames(typeof(Foo)).Distinct().Count();
        var distinctValueCount = ((Foo[])Enum.GetValues(typeof(Foo))).Distinct().Count();

        Console.WriteLine($"{nameof(nameCount)}: {nameCount}");
        Console.WriteLine($"{nameof(valueCount)}: {valueCount}");
        Console.WriteLine($"{nameof(distinctNameCount)}: {distinctNameCount}");
        Console.WriteLine($"{nameof(distinctValueCount)}: {distinctValueCount}");
    }
}

nameCount: 3
valueCount: 3
distinctNameCount: 3
distinctValueCount: 2

[andrewlock]

That's a good point. I guess one question I have is: when would you use this 🤔 i.e. when would you want to get the number of names/values but not get the actual name/values themselves?

[adamradocz]

I usually use the number of names, when I want to create a new List<T> with an initial size of the enum.
I can't think of anything right now, when would I use the distinct value count.

[andrewlock]

Thanks all, looks good to me (I added the xmldocs for clarity)