Let's say that we go with public, moduleprivate, fileprivate, scopeprivate
Would it really make sense to allow extensions in other files to access fileprivate members/funcs? The inclusion of the word 'file' in the name would make it confusing that extensions have the special power to reach into a fileprivate from another file. This almost begs for another access like typeprivate (I am not proposing this). My understating is that scopeprivate came about as a way to deal with extensions, perhaps the author needs to look into a way to tag methods/members as not extendable or hidden from extensions only. The solution would probably be swift specific and it should probably brake out from the norm of other languages. > On Mar 28, 2016, at 5:46 AM, Ross O'Brien via swift-evolution > <[email protected]> wrote: > > Ilya said: > > "public", "protected", and "private" have a very well defined meaning in > > OOP. We shouldn't redefine them without a good reason. > > I agree. Swift has a scope-based visibility system, not a type-based > visibility system, but because Swift redefines the terms 'public' and > 'private', programmers keep getting confused about how they're used in Swift. > > Over the last few posts, since Chris Lattner proposed switching to: 'public, > internal, X, private', we've had several new scales proposed. (In every scale > in this post, there are four terms in order of decreasing visibility, with > the second term being the default.) > > public, external, internal, private. > public, internal, private, secret. > external, internal, public, private. > public, internal, private, secret. > public, internal, private, local. > > At this point, respectfully, I think we can dismiss the idea that labelling > any given level as 'public' or 'private' is right or obvious. Swift is built > around clarity at the point of use. 'private' is not as clear as you maintain > it is. > > > Swift allows extensions, so "private" in its standard form doesn't work > > well -- you could just define an extension and get access to anything. The > > scope based private seems to be the most natural extension (pun intended > > :–)). > > We're redefining terms from a type-based visibility scale to a scope-based > visibility scale. I'm not disagreeing that an extension would allow access to > type-visible symbols and that this might not be the programmer's intention, > but that 'private' has a clear meaning in OOP and repurposing 'private' is > not resolving any confusion. > > > I'd like to keep "private" to be completely private and not allow class > > injection to gain access, but this is an edge case that could be argued > > either way. I can definitely live with a pure scoped access for > > consistency and don't want to argue the edge case in a never ending > > discussion. > > As far as I know, it's not an edge case in Swift, it's a non-case. Swift > doesn't have type-based visibility. Using Swift's system, I do understand > that you want 'private' to refer to the least-visible level in the hierarchy. > > However, as has already been pointed out, the scope-visible level is not the > least-visible conceivable. There's already discussion over whether the > properties of inner types should be visible to their outer types. If that > ever made its way to a proposal, would that level become 'private'? I think > we can agree that another bikeshedding conversation like this would rather be > avoided. > > There's also the possibility of a 'submodule' level. Chris Lattner suggested > that the 'private(foo.bar)' syntax might be best for this, but I don't know > what that means - whether 'submodule' would be within the Swift hierarchy or > not - but it's a possibility for the future. > > I'm repeating myself, but: inclusion of the terms 'module', 'file', and > 'scope' in our symbols is winning out in clarity. None of those terms has > changed meaning in the entire discussion. The only question is exactly how > they should be welded to the term 'private'. There've been three suggestions > for doing this so far and they're all awkward, either because they have > parentheses or they're conjoined, but they're unambiguous in meaning and > no-one's suggested any single-word ideas with the same clarity. > > public, private(module), private(file) and private(scope). > public, moduleprivate, fileprivate, scopeprivate. > public, privatetomodule, privatetofile, privatetoscope. > > I'm tempted to go one further, but if you want to ignore that one further, > skip the next two paragraphs: > > Abandon the words 'public' and 'private'. Let's just accept that, together > with 'protected', these are well-defined terms of type-based visibility in > OOP which are orthogonal to Swift's hierarchy, and that redefining them leads > to confusion. Embrace 'external' and 'internal' in their places: > > external, internal(module), internal(file), internal(scope). > external, moduleinternal, fileinternal, scopeinternal. > external, internaltomodule, internaltofile, internaltoscope. > > If you ignored that, welcome back. > > I hope I've not been too antagonistic about this. I really want Swift to use > terms with clear meaning, and if that breaks code, I want a clean break that > can be easily healed / migrated. > > Every suggestion for relabelling this hierarchy, bar 'public, internal, > private, local/scope', breaks code. > > Adding the scope-visible level allows for greater control, but I don't > believe module-visible and file-visible levels would be uncommon with its > inclusion, so the terms for all three - all four, really - should be balanced > in their 'ugliness'. > > What the proposal as it stands does need to make clear is what would change > and what would be left behind. > > If 'internal' is renamed to 'moduleprivate', explicit uses of 'internal' need > to be replaced. > > If there are constants, 'global' functions, operators, or anything that can > be defined outside of a scope, their least visible level is fileprivate. They > can never be 'scope-private'. > > If 'private' is redefined, it is no nearer to its meaning in other languages > than it is now. > > >> On Mon, Mar 28, 2016 at 12:30 PM, Matthew Judge via swift-evolution >> <[email protected]> wrote: >> >> >>> On Mon, Mar 28, 2016 at 6:41 AM, Ilya Belenkiy <[email protected]> >>> wrote: >>> lexical scope is the other way around: "inner" can see "outer". For example: >>> >>> func f() { >>> let outer = 0 >>> // f cannot use inner >>> func g() { >>> let inner = 1 >>> // g can use outer >>> } >>> } >> >> Maybe I'm off in my terminology, but I think my code example matches what >> you are saying here (outer is visible to g() but inner is not visible to f() >> >>> It would work the same way for the access level. That said, I'd rather not >>> include this in the proposal. >> >> So as the proposal stands now, what is the scope that innerVar is visible to >> in the following code: Inner or Outer? >> >> class Outer { >> class Inner { >> private var innerVar: Int >> } >> } >> >>> The only change that the core team requested was the name changes. I >>> personally would prefer a completely private version where you cannot >>> inject a class into a scope to get access to the scope internals, but it's >>> an edge case that could be argued either way, and I don't want to start >>> another lengthy discussion. We already had quite a few. >>> >>>> On Sun, Mar 27, 2016 at 11:17 PM Matthew Judge <[email protected]> >>>> wrote: >>>> I know it was suggested that it be the subject of a different thread, but >>>> it might be good to clarify how the new private is going to work (or at >>>> least what is currently envisioned). >>>> >>>> My understanding is that the new private would be: >>>> - visible only to the immediately enclosing scope >>>> - including the scope of a inner nested scope >>>> - not including the scope of an outer nested scope >>>> - not visible to an extension >>>> >>>> Said in code (all in the same file): >>>> ---------- >>>> class Outer { // Outer visible to module >>>> private var a: Int // visible to Outer, Inner1, & Inner2 >>>> >>>> class Inner1 { // Inner1 visible to module >>>> private var b: Int // visible to Inner1 only >>>> } >>>> private class Inner2 { // visible to Outer & Inner(s) >>>> var c: Int // visible to Outer & Inner(s) >>>> } >>>> } >>>> >>>> extension Outer { // visible to module >>>> // 'a', 'b', and 'Inner2' NOT visible >>>> } >>>> ---------- >>>> If this is the intended meaning of private, then fileprivate seems to be >>>> the same as private (private to the enclosing scope... which happens to be >>>> the file). >>>> >>>> Something declared "private" at the top level of a file is fileprivate. >>>> There would still need to be a way to reference scopes other than the >>>> immediate one (especially since there is no way to say "private" and mean >>>> moduleprivate), though I think it would strengthen the argument for >>>> something along the lines of "private(file)", since it would even further >>>> reduce the cases where you are spelling something more than just "private" >>>> >>>> >>>>> On Mar 27, 2016, at 17:31, Haravikk via swift-evolution >>>>> <[email protected]> wrote: >>>>> >>>>> >>>>>> On 27 Mar 2016, at 19:34, Jose Cheyo Jimenez via swift-evolution >>>>>> <[email protected]> wrote: >>>>>> >>>>>> Public >>>>>> External (default) >>>>>> Internal >>>>>> Private >>>>> >>>>> I still feel like these are still too vague; I’m not sure I like the use >>>>> of external, as public to me is external since it exports outside of the >>>>> module, whereas what you’re proposing is in fact just limited to the >>>>> module itself. I dislike the current internal keyword too, but at least >>>>> it reads as “internal to this module", this is why the more specific >>>>> terms are better like: >>>>> >>>>> public as-is, item is public/exported outside >>>>> of module >>>>> private(module) or private current internal, item is private to >>>>> this module, would be the default >>>>> private(file) current private, item is private to >>>>> this file >>>>> private(scope) new visibility type, item is private to >>>>> the current scope >>>>> >>>>> Assuming I’m understanding the restriction properly this time =) >>>>> >>>>> It’s also the easiest method if we do add another visibility later for >>>>> sub-classes such as private(type), as it doesn’t even require a new >>>>> keyword. >>>> >>>>> _______________________________________________ >>>> >>>>> >>>>> swift-evolution mailing list >>>>> [email protected] >>>>> https://lists.swift.org/mailman/listinfo/swift-evolution >> >> >> _______________________________________________ >> swift-evolution mailing list >> [email protected] >> https://lists.swift.org/mailman/listinfo/swift-evolution > > _______________________________________________ > swift-evolution mailing list > [email protected] > https://lists.swift.org/mailman/listinfo/swift-evolution
_______________________________________________ swift-evolution mailing list [email protected] https://lists.swift.org/mailman/listinfo/swift-evolution
