[webkit-dev] Get rid of RefPtr, replace with std::optional<Ref>?
fpizlo at apple.com
Fri Sep 1 10:15:27 PDT 2017
> On Sep 1, 2017, at 10:09 AM, Chris Dumez <cdumez at 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.
> Chris Dumez
>> On Sep 1, 2017, at 9:46 AM, Maciej Stachowiak <mjs at apple.com <mailto:mjs at apple.com>> wrote:
>>> On Sep 1, 2017, at 9:30 AM, Brady Eidson <beidson at apple.com <mailto:beidson at 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?"
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