What was added in Swift 3 was `private`; the old `private` was renamed `fileprivate` with no change in behavior. Certainly, submodules are a big topic that deserves careful consideration. But the question being discussed here is about rolling back the change that was implemented in Swift 3 by removing `private` and restoring `fileprivate` to its old name.
On Sun, Feb 12, 2017 at 8:08 PM, Dietmar Planitzer via swift-evolution < swift-evolution@swift.org> wrote: > Fileprivate is a feature that should not have been added to Swift 3 > because it is in the end just a needlessly limited version of the Java > package access level. Fileprivate forces me to put all types which are > related on an implementation level into the same file while Java packages > allow me to put each type implementation into a separate file. The only > thing that Java requires is that all files which are part of the same > package are tagged with the same package id. Java’s package access level is > more powerful than fileprivate because it gives me more freedom in how I > want to organize my code while still making sure that code in sibling and > parent packages can not access symbols inside my package which form part of > the implementation details of my package. > > The first thing that needs to happen before any more access levels are > added is that a concept of sub-modules is added to Swift along the lines of: > > 1) modules can be organized into a tree with one module as the root. > > 2) all modules which are nodes in the same module tree form a single > resilience domain. > > IMO, the sub-module stuff should be designed similar if not the same way > as Java packages because there are already lots and lots of SDEs who know > how Java packages work, and Java packages are well understood, simple and > straight-forward in their mechanics. > > Once sub-modules are in place, it makes sense to revisit the access level > topic. Eg in order to add a “module” access level that represents the scope > of a module. So “module” could then do what file private can do today plus > more. But we should stop trying to add more access level to the language > until then. We also need to look much more at the bigger picture of things > instead of getting too much hung up on a single component of a larger > mechanism, when it is that larger mechanism that is primarily interesting > and relevant. > > > > Regards, > > Dietmar Planitzer > > > On Feb 12, 2017, at 16:16, Zach Waldowski via swift-evolution < > swift-evolution@swift.org> wrote: > > > > I vehemently agree on these points. New-private and fileprivate "[add] > more information" to a file the same way requiring `self.` and other sorts > of visual noise that Swift normally eschews. > > > > I wish for the Swift community to be introspective enough to count both > its successes and failures. SE-0025 was a botched addition to the language. > That the migrator did such a bad job is evidence of its poor overall > consideration. Adding a fix-it strikes me as the compiler waggling its > finger at me for code that would've been perfectly fine in the past, > something that it is not at all true with the "let" fix it; accidental > mutation has been discussed a ton by the larger programming community, > not-so-much for obscure access control mechanics. > > > > It's perplexing that fileprivate advocates continue to stand on mostly > theoretical benefits about new-private. I feel nothing for the mathematical > purity about the types in a file. In practice, I can with much experience > now how awful it is. There has been no end to the confusion its > introduction has inflicted upon my team(s), people new to the language, and > people revisiting the language: > > > > - My teams and coworkers are less effective at code review from constant > litigation about access control. "'Did this need to change?' / 'No, it was > just the migrator.'" has become a disturbingly common refrain. > > > > - New users are just struggling to figure out where to put the curly > braces in the first place. Having to make them check and re-check where > things go in a file, or just tell them to use this clunky > get-out-of-jail-free keyword, feels like visiting a special kind of > Pythonic hell on a language I otherwise love and love to teach. > > > > - People returning to the language feel (and often say - just look at > Twitter) Swift has a lot of syntax, and are frustrated that the addition of > a new keyword was burned on adding something that amounts to mostly a > stylistic opinion. > > > > All the best, > > Zachary Waldowski > > z...@waldowski.me > > > > On Sun, Feb 12, 2017, at 04:45 PM, Xiaodi Wu via swift-evolution wrote: > >> On Sun, Feb 12, 2017 at 3:24 PM, Matthew Johnson < > matt...@anandabits.com> wrote: > >> > >> > >>> On Feb 12, 2017, at 2:35 PM, Xiaodi Wu via swift-evolution < > swift-evolution@swift.org> wrote: > >>> > >>> _Potentially_ meaningful, certainly. But what I'm hearing is that it > isn't actually meaningful. Here's why: > >>> > >>> If I see `fileprivate` and can understand that to mean "gee, the > author _designed_ this member to be visible elsewhere inside the file," > then it's actually meaningful. OTOH, if I see `fileprivate` and can only > deduce "gee, the author mashed some button in his or her IDE," then it's > not really telling me anything. > >> > >> > >> You’re looking at it backward. It’s when you see `private` and can > deduce “this member is only visible inside it’s declaring scope” that can > be really helpful. *This* is what matters. > >> > >> In what ways can that information help you? > >> > >> > >>> What you've said above, as I understand it, is that it's not currently > meaningful to see `fileprivate` because the migrator is writing it and not > the author. The improved approach you proposed is the additional warning. > In that case, the compiler will help to ensure that when I see > `fileprivate`, at least I know it's necessary. But that's only telling me a > fact (this member is accessed at least once outside the private scope), but > it's still machine-based bookkeeping, not authorial intent. > >> > >> > >> The important thing is that this machine-based bookkeeping results in a > proof about the code. This facilitates reasoning about the code. You can > make an argument that this proof is not important enough to matter, but you > must admit that this is a real concrete gain in information that is > immediately available to a reader of the code (after they know that it > compiles). Personally, I find this proof to be valuable. > >> > >> Comparison has been made to `let` and `var`. In that case, whether a > variable is mutated can be non-trivial to deduce (as Swift has no uniform > scheme for distinguishing mutating from non-mutating functions; the ed/ing > rule has many exceptions). By contrast, here, I don't see any gain in > information. You can literally *see* where the (file)private member is > accessed, and when a file gets too long, even a simple text editor can do a > decent enough find. > >> > >> If you're right that the real value is that seeing `private` helps you > reason about the code, then that value must be commensurate to how often we > see Swift users amending the migrator to take advantage of it. For me, the > compelling evidence that Swift users don't find this proof to be valuable > is that, by examination of Swift 3 code, Swift users haven't bothered. If > we add a new fix-it to force them to, then of course they'll mash the > buttons, but it's pretty much declaring that they are wrong not to care > about what it seems they do not care at present. > >> > >>> On Sun, Feb 12, 2017 at 2:14 PM, Chris Lattner <sa...@nondot.org> > wrote: > >>> I don't fully agree: you are right that that is the case when writing > code. However, when reading/maintaining code, the distinction is > meaningful and potentially important. > >>> > >>> -Chris > >>> > >>> > >>> On Feb 12, 2017, at 12:02 PM, Xiaodi Wu <xiaodi...@gmail.com> wrote: > >>>> If the overwhelming use case is that developers should pick one over > the other primarily because it looks nicer, then blindly click the fix-it > when things stop working, then the distinction between private and > fileprivate is pretty clearly a mere nuisance that doesn't carry its own > weight. > >>>> On Sun, Feb 12, 2017 at 13:33 Jean-Daniel via swift-evolution < > swift-evolution@swift.org> wrote: > >>>>> Le 12 févr. 2017 à 18:24, Chris Lattner via swift-evolution < > swift-evolution@swift.org> a écrit : > >>>>> > >>>>> On Feb 12, 2017, at 8:19 AM, David Hart via swift-evolution < > swift-evolution@swift.org> wrote: > >>>>>> Final > >>>>>> Can someone tell me what is the use of 'final' now that we have > 'public' default to disallowing subclassing in importing modules? I know > that 'final' has the added constraint of disallowing subclassing in the > same module, but how useful is that? Does it hold its weight? Would we add > it now if it did not exist? > >>>>> > >>>>> As Matthew says, this is still important. > >>>>> > >>>>>> Lazy > >>>>>> This one is clearer: if Joe Groff's property behaviors proposal > from last year is brought forward again, lazy can be demoted from a > language keyword to a Standard Library property behavior. If Joe or anybody > from the core team sees this: do we have any luck of having this awesome > feature we discussed/designed/implemented in the Swift 4 timeframe? > >>>>> > >>>>> Sadly, there is no chance to get property behaviors into Swift 4. > Hopefully Swift 5, but it’s impossible to say right now. > >>>>> > >>>>>> Fileprivate > >>>>>> > >>>>>> I started the discussion early during the Swift 4 timeframe that I > regret the change in Swift 3 which introduced a scoped private keyword. For > me, it's not worth the increase in complexity in access modifiers. I was > very happy with the file-scope of Swift pre-3. When discussing that, Chris > Latner mentioned we'd have to wait for Phase 2 to re-discuss it and also > show proof that people mostly used 'fileprivate' and not the new 'private' > modifier as proof if we want the proposal to have any weight. Does anybody > have a good idea for compiling stats from GitHub on this subject? First of > all, I've always found the GitHub Search quite bad and don't know how much > it can be trusted. Secondly, because 'private' in Swift 2 and 3 have > different meanings, a simple textual search might get us wrong results if > we don't find a way to filter on Swift 3 code. > >>>>> > >>>>> I would still like to re-evaluate fileprivate based on information > in the field. The theory of the SE-0025 (https://github.com/apple/ > swift-evolution/blob/master/proposals/0025-scoped-access-level.md) was > that the fileprivate keyword would be used infrequently: this means that it > would uglify very little code and when it occurred, it would carry meaning > and significance. > >>>> > >>>> Infrequent use and significance are orthogonal. > >>>> I still think developers would declare all ivars private (this is > less ugly and shorter), and then will happily convert them to fileprivate > each time the compiler will tell them they are not accessible somewhere > else in the file. > >>>> As the code that try to access that ivar is in the same file anyway, > it has full knowledge of the implementation details and there is no good > reason it shouldn’t be able to access the ivar when needed. > >>>> > >>>>> We have a problem with evaluating that theory though: the Swift 2->3 > migrator mechanically changed all instances of private into fileprivate. > This uglified a ton of code unnecessarily and (even worse) lead programmers > to think they should use fileprivate everywhere. Because of this, it is > hard to look at a random Swift 3 codebase and determine whether SE-0025 is > working out as intended. > >>>>> > >>>>> The best way out of this that I can think of is to add a *warning* > to the Swift 3.1 or 4 compiler which detects uses of fileprivate that can > be tightened to “private” and provide a fixit to do the change. This would > be similar to how we suggest changing ‘var’ into ‘let’ where possible. > Over time, this would have the effect of getting us back to the world we > intended in SE-0025. > >>>>> > >>>>> -Chris > >>>>> > >>>>> _______________________________________________ > >>>>> swift-evolution mailing list > >>>>> swift-evolution@swift.org > >>>>> https://lists.swift.org/mailman/listinfo/swift-evolution > >>>> _______________________________________________ > >>>> swift-evolution mailing list > >>>> swift-evolution@swift.org > >>>> https://lists.swift.org/mailman/listinfo/swift-evolution > >>> > >>> _______________________________________________ > >>> swift-evolution mailing list > >>> swift-evolution@swift.org > >>> https://lists.swift.org/mailman/listinfo/swift-evolution > >> _______________________________________________ > >> swift-evolution mailing list > >> swift-evolution@swift.org > >> https://lists.swift.org/mailman/listinfo/swift-evolution > > > > _______________________________________________ > > swift-evolution mailing list > > swift-evolution@swift.org > > https://lists.swift.org/mailman/listinfo/swift-evolution > > _______________________________________________ > swift-evolution mailing list > swift-evolution@swift.org > https://lists.swift.org/mailman/listinfo/swift-evolution >
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