On Sep 1, 2017, at 10:09 AM, Chris Dumez <cdumez@apple.com> wrote:

I think std::optional<Ref<Type>> looks ugly. Also, unlike RefPtr<>, I do not think it is copyable. It is pretty neat to be able to capture a RefPtr<> by value in a lambda.
Also, how do you convert it to a raw pointer? myOptionalRef.value_or(nullptr) would not work. Not sure there would be a nice way to do so.

Finally, the storage space argument from Maciej is a good one.

We could create a specialization for std::optional<Ref>.  Filed: https://bugs.webkit.org/show_bug.cgi?id=176228

That seems like a good idea separately from whether it should be used instead of RefPtr.  Even if we did have style prohibiting it, we might end up with such a type because of template specialization.

I can see cases were std::optional<Ref> works more naturally into the surrounding code than RefPtr.  That probably happens if your code is already based on Ref.  In my experience there’s a lot of inertia to these things - once some code uses RefPtr enough, it can be awkward to introduce Ref and perhaps vice versa.  I don’t find it very hard to switch between thinking in terms of Ref and RefPtr, so I don’t mind that our code uses both.  I wouldn’t agree with a style that encourages using std::optional<Ref> instead of RefPtr, but I also wouldn’t want to disallow it.

-Filip


 
--
 Chris Dumez




On Sep 1, 2017, at 9:46 AM, Maciej Stachowiak <mjs@apple.com> wrote:



On Sep 1, 2017, at 9:30 AM, Brady Eidson <beidson@apple.com> wrote:

I recently worked on a patch where - because of the organic refactoring of the patch over its development - I ended up with a std::optional<Ref> instead of a RefPtr.

A followup review after it had already landed pointed this out, and it got me to thinking:

Does RefPtr do anything for us today that std::optional<Ref> doesn’t?

The obvious things would be: uses less storage space, has a shorter name.


I kind of like the idea of replacing RefPtr with std::optional<Ref>. It makes it explicitly clear what object is actually holding the reference, and completely removes some of the confusion of “when should I use Ref vs RefPtr?"

Thoughts?

Thanks,
~Brady
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