C#'s ??-Operator in Unity

Hi folks,

can anyone explain me the diffrence between this two code segments?
They should do the same, but somehow the ??-Operator fails

Code (CSharp):

1. public InventarItem(InventarItem _original)
2. {
3. m_ID = _original.m_ID;
4. m_Name = _original.m_Name;
5. m_Picture = _original.m_Picture ?? InventarController.Instance.m_DefaultPicture; // does not work if _original.m_Picture is null
6. }
7. public InventarItem(InventarItem _original)
8. {
9. m_ID = _original.m_ID;
10. m_Name = _original.m_Name;
11. m_Picture = _original.m_Picture != null ? _original.m_Picture : InventarController.Instance.m_DefaultPicture; // works
12. }

 

Unity has overridden the == operator to return things as null, even when they're not, and vice versa.
http://docs.unity3d.com/ScriptReference/Object-operator_eq.html

When you call Destroy(gameObject), the gameObject is not instantly removed from memory - it's kept around in a "destroyed" state. Unity's == override takes this into account, so if you compare a "destroyed" state gameObject to null with ==, it works as you'd expect. But, the null coalescing operator (??) doesn't have a clue what's going on, so it sees the object and returns it as non-null.

Sucky, but that's why.

 

Ok, thank you, this makes a lot of sense...

So the null coalescing operator won't work with any classes provided by unity?

 

Nothing that derives from UnityEngine.Object

 

Is there a reason for overloading == and not ??, or is overloading ?? something we should request from Unity?

 

AFAIK you actually can't overload the coalescing operator.

 

C# doesn't allow ?? overrides - just ==.