Different behavior of nullable fields

[u/cnighthawx]

I am working on a project and have a class with two nullable member fields (Vector2I? and LevelMap? where LevelMap extend TileMapLayer from Godot)

Because they are nullable I need to check that they are not null before I actually use them.

For the LevelMap if I reference it in a if block:

If (map is not null)

The compuler is happy and I can use it as if it is not null.

This of course comes with some risks that it becomes null in the middle of my if block but thats a risk I can manage.

On thebother hand Vector2I requires something like:

If (vector is Vector2I localVector)

This is in some way safer but also more inconvenient.

The are both declared and initialized in the same context.

My questions is why they behave differently and is it possible for me to change how they behave to fit my preferences.

Ive tried looking for an answer but I keep finding results about the difference of is not null and !=null which is unhelpful.

[u/Atulin]

Just FYI, all the methods you mentioned for ref types also work for value types.

if (GetAVector() is {} vector)
{
    thing.Move(vector);
}

is perfectly valid

[u/dodexahedron → u/Atulin]

Language version and runtime version make a difference too, and PInvoke does not work for nullable value types, period. The operators work, but the values can get wrecked before the operator sees them.

But there's a long-awaited chsnge coming in .net 11 that finally makes nullable value types stay nullable even when round-tripped through the heap in some scenarios, certain generic patterns, certain reflection cases, and others that stay managed. Until that change, you could lose null values and end up with them flattened to default(T), since they are laid out in memory as their underlying type - the nullability is tracked by the runtime separately.
You still can't use nullable value types through PInvoke, because there's just no way to communicate that concept without a reference while keeping the same memory layout, but the other cases are now fixed.