919222 - Add AutoPtr to MFBT

Status: RESOLVED INVALID

(Core :: MFBT, defect)

Description

[Benoit Jacob [:bjacob] (mostly away)]

Attachment: Add AutoPtr to MFBT

I am trimming various gfx/ headers like gfxASurface.h and a problem is that they have to include nsAutoPtr.h, which is make expensive to include by being also the header for nsRefPtr, which means that it drags in a lot of XPCOM stuff, like around cycle collection.

How about having a AutoPtr class in MFBT instead?

We had a AutoPtr class in js/src/ctypes/CTypes.h already. The present class is mostly just a MFBT-ificiation of it. I followed it, rather than the more featureful nsAutoPtr, because we can always add features later if the appear as needed.

In particular, note that like the one in ctypes/, this AutoPtr class doesn't cast to T*. You have to call .get() or use !! to evaluate as a bool. There is a comment, copied from the ctypes/ file, explaining why. The nsAutoPtr class solves this in a nontrivial way (see the Ptr nested class inside of it). That looked complicated enough that I'd rather hold off from doing it until someone really needs it.

Comment 1

[Joshua Cranmer [:jcranmer]]

The auto_ptr mentality is broken, and it is deprecated in C++11. You really should make it UniquePtr instead and make it act like std::unique_ptr.

Comment 2

[Jeff Muizelaar [:jrmuizel]]

(In reply to Joshua Cranmer [:jcranmer] from comment #1)
> The auto_ptr mentality is broken, and it is deprecated in C++11. You really
> should make it UniquePtr instead and make it act like std::unique_ptr.

Yes please. Having a UniquePtr class would be lovely.

Comment 3

[Benoit Jacob [:bjacob] (mostly away)]

Nevermind, Nathan points out that MFBT already has ScopedDeletePtr which is exactly the same thing.