Units property should not include Undefined value

[angularsen]

https://github.com/angularsen/UnitsNet/blob/master/UnitsNet/GeneratedCode/Quantities/Length.g.cs#L164

Similar for all quantities, Length only chosen as an example.

It doesn't make sense to include the LengthUnit.Undefined = 0 value, since it is not meant to be used. UnitsNet will throw exception if you try to use this value for anything in methods accepting a unit value, as the intent is to help you catch bugs where you forgot to initialize the value such as when deserializing data.

[bplubell]

If we remove Undefined, should we set the first value to be a value other than 0 (like Centimeter = 1 instead of Centimeter = 0.)?

Is this considered a breaking change, since someone may be be doing their own checking for something like LengthUnit.Undefined?

[angularsen]

Updated link:

UnitsNet/UnitsNet/GeneratedCode/Quantities/Length.g.cs

Lines 161 to 164 in 5f2b075

	/// <summary>
	/// All units of measurement for the Length quantity.
	/// </summary>
	public static LengthUnit[] Units { get; } = Enum.GetValues(typeof(LengthUnit)).Cast<LengthUnit>().ToArray();

As you can see, I didn't mean to remove the Undefined enum value definition, I only meant to exclude it from the list of units in Length.Units property.

The motivation for this change, which I forgot to mention in the description, is that some people complained Undefined was listed when they were enumerating all Length units and I agree it's not intuitive and I don't see any purpose in keeping that value.

I would not consider this a breaking change, as I rather consider it a bug that the value was included to begin with.

The code change would be something like

public static LengthUnit[] Units { get; } = Enum.GetValues(typeof(LengthUnit)).Cast<LengthUnit>().Except(new[]{LengthUnit.Undefined}).ToArray(); 

[bplubell]

Ah, that does make more sense. I am submitting a PR to do this - I just took your suggested solution.