Bug during null check

[NilesDavis]

I came in a situation where I checked a Polygon2D if it was null or not and in any case it returned false. Try this code to reproduce:

Polygon2D polygon = null;
bool isNull = polygon == null;

The variable isNull should result in being true, but is not!

Essentially what is missing in the "=="-operator is something like this:

//both null
if (ReferenceEquals(left, null) && ReferenceEquals(right, null))
    return true;
//for null-condition
if (ReferenceEquals(left, null) || ReferenceEquals(right, null))
    return false;

This seems to be the same situation for nearly all classes of Euclidian namespace!

• CoordinateSystem (null-condition NOT checked)
• PolyLine2D (null-condition is checked)
• PolyLine3D (null-condition is checked)
• Polygon2D (null-condition is checked)

Or am I missing something? As mathnet-spatial mostly uses structs it is not that obvious

[jkalias]

Hi @NilesDavis,

Thanks for the feedback. This seems indeed like a bug. I don't need a proper definition for ==, neither for PolyLine2D which you say is implemented properly. Would you mind opening a PR (including unit tests)?

Thanks

[NilesDavis]

Hi @jkalias . To be honest, I wanted to, but I couldnt get the build Environment running for Standard 2.0 in VS2022. That kept me of doing it, sorry. You know the code is not the problem but tooling is... So you have it running that you can compile it?

Cheers, Nils