The review of SE-0098: "Lowercase didSet and willSet for more consistent keyword casing" ran from May 24…30, 2016. The proposal is rejected for Swift 3.
The feedback on the proposal from both the core team and the community was that these should remain camel cased, particularly given that they may become user-definable aspect names in a future release.
Many thanks to Erica Sadun for driving this discussion and writing the proposal. This was an important topic for the community and core team to re-evalute.
For those of us who participated in this forum in 2021, this rationale was difficult to understand. I read this thread and SE-0030, and found that the 'user-definable aspect names in a future release' is mostly relating to a feature of 'property behaviors'. And in 2016, it had been thought that
willSet would be one of 'accessors' which would be also definable by users. Therefore, people in the discussion worried that renaming
didset would cause users to name their custom accessors in lowercase, and rejected the proposal.
(Please tell me if I'm misunderstanding)
I agree this was convincing reason in 2016. However, now there is an introduced alternative feature 'property wrappers'. When it was called 'property delegates', the author of the proposal explained the difference as:
As this quote, property wrappers are alternative feature of property behaviors. Now property wrappers were introduced and we can say property behaviors won't be added in the future. So now there is nothing to worry to rename
didset/willset, except that it is a source breaking change .
As said in that thread, Swift6 would be a great opportunity to fix this inconsistency, and I think SE-0098 should be revisited.