This sentence in the Motivation sentence is confusing:
Before offering solutions, lets discuss how and why it can be viewed as
actiely harmful, the new requirement for syntax/API changes.
I would suggest rewording it as follows:
Before offering solution, let’s discuss how and why it can be viewed as
actively harmful (which is the new requirement for syntax/API changes.)
My initial parsing of this sentence was “let’s discuss how the new requirement
for syntax/API changes can be viewed as actively harmful”, which is not the
intended meaning.
-BJ
> On Feb 20, 2017, at 11:58 PM, David Hart via swift-evolution
> <[email protected]> wrote:
>
> Hello list,
>
> Matthew Johnson and I have been putting our proposals together towards a
> joint “let’s fix private access levels” proposal. As the community seems
> quite divided on the issue, we offer two solutions in our proposal to let the
> community debate and to let the core team make the final decision.
>
> I’d like to concentrate this round of feedback on the quality of the
> proposal, and not on the merits of Solution 1 or 2. thoughts?
>
> https://github.com/hartbit/swift-evolution/blob/fix-private-access-levels/proposals/XXXX-fix-private-access-levels.md
>
> <https://github.com/hartbit/swift-evolution/blob/fix-private-access-levels/proposals/XXXX-fix-private-access-levels.md>
>
> David.
>
> Fix Private Access Levels
>
> Proposal: SE-XXXX
> <https://github.com/hartbit/swift-evolution/blob/fix-private-access-levels/proposals>
> Authors: David Hart <http://github.com/hartbit>, Matthew Johnson
> <https://github.com/anandabits>
> Review Manager: TBD
> Status: TBD
>
> <https://github.com/hartbit/swift-evolution/tree/fix-private-access-levels#introduction>Introduction
>
> This proposal presents the problems the came with the the access level
> modifications in SE-0025
> <https://github.com/apple/swift-evolution/blob/master/proposals/0025-scoped-access-level.md>
> and presents two community driven solutions to fix them. As a consensus will
> not easily emerge, this proposal will allow a last round of voting and let
> the core team decide. Once that is done, this proposal will be ammended to
> describe the chosen solution.
>
>
> <https://github.com/hartbit/swift-evolution/tree/fix-private-access-levels#motivation>Motivation
>
> Since the release of Swift 3, the access level change of SE-0025 was met with
> dissatisfaction by a substantial proportion of the general Swift community.
> Before offering solutions, lets discuss how and why it can be viewed as
> actiely harmful, the new requirement for syntax/API changes.
>
>
> <https://github.com/hartbit/swift-evolution/tree/fix-private-access-levels#criticisms-of-se-0025>Criticisms
> of SE-0025
>
> There are two primary criticism that have been offered.
>
> The first is that private is a "soft default" access modifier for restricting
> access within a file. Scoped access is not a good behavior for a "soft
> default" because it is extremely common to use several extensions within a
> file. A "soft default" (and therefore private) should work well with this
> idiom. It is fair to say that changing the behavior of private such that it
> does not work well with extensions meets the criteria of actively harmful in
> the sense that it subtly encourages overuse of scoped access control and
> discourages the more reasonable default by giving it the awkward name
> fileprivate.
>
> The second is that Swift's system of access control is too complex. Many
> people feel like restricting access control to scopes less than a file is of
> dubious value and therefore wish to simplify Swift's access control story by
> removing scoped access. However, there are many others who like the ability
> to have the compiler verify tighter access levels and believe it helps make
> it easier to reason about code which is protecting invariants.
>
>
> <https://github.com/hartbit/swift-evolution/tree/fix-private-access-levels#detailed-design>Detailed
> design
>
> Both authors agree that the private keyword should be reverted back to its
> Swift 2 file-based meaning, resolving the first criticism. But the authors
> disagree on what should be done about the scoped access level and the
> following solutions represent the two main opinions in the community:
>
>
> <https://github.com/hartbit/swift-evolution/tree/fix-private-access-levels#solution-1-remove-the-scoped-access-level>Solution
> 1: Remove the scoped access level
>
> Compared to a file-based access level, the scoped-based access level adds
> meaningful information by hiding implementation details which do not concern
> other types or extensions in the same file. But is that distinction between
> private and fileprivate actively used by the larger community of Swift
> developers? And if it were used pervasively, would it be worth the cognitive
> load and complexity of keeping two very similar access levels in the
> language? This solution argues that answer to both questions is no and that
> the scoped access level should be removed to resolve the complexity criticism.
>
> This solution has the added advantage of leaving the most design
> breathing-room for future discussions about access levels in regards to
> submodules.
>
>
> <https://github.com/hartbit/swift-evolution/tree/fix-private-access-levels#solution-2-rename-the-scoped-access-level-to-scoped>Solution
> 2: Rename the scoped access level to scoped
>
> It is difficult to make the case that a feature which a nontrivial number of
> Swift users find valuable and which is easy for teams to avoid is actively
> harmful. It seems like something that falls more into the category of a
> debate over style (which could be addressed by a linter). Should we remove a
> feature whose utility is a question of style, but is not actively harmful in
> the sense of causing programmer error? The second solution argues against it
> and proposes renaming it to scoped.
>
> The scoped keyword is a good choice not only because the community has been
> calling this feature “scoped access control” all along, but also because the
> principle underlying all of Swift’s access levels is the idea of a scope.
>
>
> <https://github.com/hartbit/swift-evolution/tree/fix-private-access-levels#source-compatibility>Source
> compatibility
>
> In Swift 3 compatibility mode, the compiler will continue to treat private
> and fileprivate as was previously the case.
>
> In Swift 4 mode, the compiler will deprecate the fileprivate keyword and
> revert the semantics of the private access level to be file based. The
> migrator will rename all uses of fileprivate to private. In solution 2, the
> migrator will also rename all uses of private to scoped.
>
> With solution 1 (and with solution 2 if the migrator is not run), cases where
> a type had private declarations with the same signature in different scopes
> will produce a compiler error. For example, the following piece of code
> compiles in Swift 3 compatibilty mode but generates a Invalid redeclaration
> of 'foo()' error in Swift 4 mode.
>
> struct Foo {
> private func bar() {}
> }
>
> extension Foo {
> private func bar() {}
> }
>
> <https://github.com/hartbit/swift-evolution/tree/fix-private-access-levels#alternatives-considered>Alternatives
> Considered
>
> Deprecate fileprivate and modify the semantics of private to include
> same-type extension scopes in the same file.
> Deprecate fileprivate and modify the semantics of private to include
> same-type extension scopes in the same module.
> The alternatives are potentially interesting but completely remove the file
> access level while making the new privateaccess level more complicated to
> explain and understand.
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