Improving constraint for BitHelper

[NN---]

public static bool GetBit<T>(T bits, byte idx) where T : IConvertible

Just wondering, did you want to specify T : unmanaged perhaps ?
Check here:
https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/generics/constraints-on-type-parameters
https://blogs.msdn.microsoft.com/seteplia/2018/06/12/dissecting-new-generics-constraints-in-c-7-3/

[dahall]

Thanks for bringing this to my attention. I hadn't seen this yet. I'll look to implement in the next release along with all the handle changes. If you have time to do a PR for this, I'd be very appreciative.

[NN---]

Did you use IConvertible in other places where thr meaning was unmanaged constraint ?

[dahall]

I tried to follow the pattern using struct, IConvertible constraints whenever specifying enum or number types. I used the struct constraint and exceptions when looking for blittable types.

[dahall]

In this particular BitHelper extension, I was attempting to constrain to the set of items that could be converted to a number.

[NN---]

So BitHelper definitely should use unmanaged to cover all blittable types.
As for enum there is Enum constraint in C# 7.3 and interesting workaround in older version.

https://stackoverflow.com/a/28527552

[NN---]

Actually if I understand correctly BitHelper is intended for types smaller or equal than Int64 ?

Is it correct ?
If yes, then a correct answer is to just have overloads for all primitive types and not using IConvertible.
In case you say it is too much code to write, just use T4.
See how CodeJam uses it to generate all required overloads: https://github.com/rsdn/CodeJam/blob/master/Main/src/Algorithms/Algorithms.EqualRange.tt

[NN---]

There is also possible NRE since you can pass null in 'bits' parameter.

[dahall]

To simplify and help make more foolproof, I have extended the list of constraints to struct, IComparable, IComparable<T>, IConvertible, IEquatable<T>, IFormattable in 2.0. Not perfect, but better.