[swift-evolution] [swift-evolution-announce] [Review] SE-0159: Fix Private Access Levels

Ross O'Brien narrativium+swift at gmail.com
Fri Mar 24 09:27:17 CDT 2017


We should be clear about this, because it seems to me that this is the
source of the 'cognitive load' problem:

Following Alternative 3,
private properties in scopes, would become "scoped".
fileprivate properties in or out of scopes would become "private".
private types, such as protocols, classes, etc., would *stay* "private".
The keyword would consistently mean private to the file, instead of
changing its meaning at different scopes.





On Fri, Mar 24, 2017 at 1:49 PM, Ricardo Parada via swift-evolution <
swift-evolution at swift.org> wrote:

> After reading the discussions it seems to me that renaming private ->
> scoped and fileprivate -> private might keep both sides happy.
>
>
>
> > On Mar 24, 2017, at 9:06 AM, Vladimir.S via swift-evolution <
> swift-evolution at swift.org> wrote:
> >
> >> On 24.03.2017 11:47, Jonathan Hull via swift-evolution wrote:
> >> Nevin had a fantastic proposal for submodules which changed private to
> mean
> >> “private to the submodule”, where each file was implicitly a submodule
> >> unless you declared otherwise.  Simple and elegant.
> >
> > Currently I don't see how submodules can eliminate the needs of
> 'scoped'(current 'private') access level. Even in submodule (even if
> submodule will be a "namespace" line feature like "submodule Name{..}" and
> we can have number of such declarations in the same file) - 'scoped' access
> is valuable even for single type declaration. Probably I don't understand
> something.
> >
> > But as for fileprivate - it is really logically to have it named
> 'private' and it can naturally be used in submodules as "private to
> submodule" just like "private to file" currently.
> >
> > So I do think the right move currently is to rename
> fileprivate->private, private->scoped and then, when(if!) we have
> submodules - we can change something.
> > Rename will remove the huge confusion users(especially novice) have with
> 'fileprivate' vs 'private'; experience shows that *actually* programmers
> use 'fileprivate' a lot and this is some kind of Swift/iOs programming
> style, and fileprivate is awkward keyword, and many(all? ;-)  just want
> 'private' means "in this file".
> > Also novice programmer can know just about 'public', 'internal' and
> 'private' - these three logically united access modifiers,all are
> file-scoped, but more experienced programmer has no problems teach what
> 'scoped' means and why one want to use it.
> >
> >>
> >>
> >>> On Mar 23, 2017, at 6:27 PM, Drew Crawford via swift-evolution
> >>> <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
> >>>
> >>>
> >>>
> >>>
> >>> Sent from my iPhone
> >>> On Mar 23, 2017, at 6:41 PM, David Hart <david at hartbit.com
> >>> <mailto:david at hartbit.com>> wrote:
> >>>
> >>>> I have difficulties imagining a submodule proposal that could allow us
> >>>> to eliminate fileprivate. Care to give an example?
> >>>
> >>> The obvious example would be Rust.  Rust has exactly two visibilities,
> >>> and merely one keyword.  By default, members are "private" which is
> >>> visible inside the module (so, like Swift's internal). The "public"
> >>> keyword is similar to Swift.
> >>>
> >>> The reason this works is that unlike in Swift where a module is
> something
> >>> like a library or framework (Rust calls those "crates"), in Rust
> modules
> >>> in are (explicitly) lexically scoped; a "mod myscope {}" module can be
> >>> created for the portion of the file for which the member should be
> >>> visible and it won't be visible outside that scope. Likewise,
> >>> "fileprivate" can be achieved by enclosing the file in a "mod MyFile
> {}".
> >>> And like all lexical scopes, they can be recursively nested to
> arbitrary
> >>> depth to achieve any number of visibility behaviors (e.g., declare a
> >>> module for the first half of two files) that would require complex new
> >>> keywords to achieve in Swift. Finally there are some shortcut features
> >>> like the ability to infer a module structure from the file system.
> >>>
> >>>
> >>>
> >>> In Swift, modules are presently tied to libraries/frameworks in a 1:1
> >>> way. Because of this we lack the flexibility of recursively nestable
> >>> modules of other languages and this is the underlying problem that
> >>> motivates both scoped/private and fileprivate.  If we fixed that, we
> >>> would actually not need either keyword.
> >>>
> >>> http://rustbyexample.com/mod/visibility.html
> >>> https://doc.rust-lang.org/book/crates-and-modules.html
> >>> _______________________________________________
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> >>> swift-evolution at swift.org <mailto:swift-evolution at swift.org>
> >>> https://lists.swift.org/mailman/listinfo/swift-evolution
> >>
> >>
> >>
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