See, the key difference between for...in and .forEach() is that one allows for continue and break and the other doesn't. Swift is not a live-and-let-live language: if you truly believe that using continue leads to bad code, then propose its removal or the removal of for...in altogether.
On Mon, Jun 13, 2016 at 11:21 let var go <letva...@gmail.com> wrote: > No, I wouldn't eliminate 'continue'. Even though I consider it a > sub-optimal solution, I would keep it in the language. Why? A couple of > reasons: > > 1) I don't like it, but even 'continue' may be the best available solution > in the context of a particular problem. I will look for other options > first, but I don't rule out the possibility that there might come a time > when it is the right tool for the job. > > 2) Some people like it. Not everyone feels the same way about it as me. > Some of the people who like it are better programmers than me. I have a lot > to learn, and someday I might discover that I love 'continue' after all. > Until then, live-and-let-live is what I say. Everyone should control their > own flow :) Keep your hands off my 'where' and I'll keep my hands off your > 'continue' :) > > On Mon, Jun 13, 2016 at 8:56 AM Xiaodi Wu <xiaodi...@gmail.com> wrote: > >> On Mon, Jun 13, 2016 at 10:44 AM, let var go <letva...@gmail.com> wrote: >> >>> I think we must be reading different discussions. >>> >>> What I have seen in this discussion is the following: >>> >>> a) The need to filter a for-in loop doesn't arise that often; but, >>> b) When it does arise, everyone who has chimed in on this thread (except >>> the two people who are proposing the change) thinks that the "where" clause >>> is the clearest, most expressive way to do it. >>> >>> Something that would help me get on board with this change is more >>> evidence about what kind of problems it is actually creating. >>> >>> As best I can tell, this proposal got started because "somewhere" some >>> new programmers (no one knows how many) expressed some confusion (no one >>> knows how seriously they were confused, or how long it took them to figure >>> it out) about how the where clause worked in a for-in loop. For all we >>> know, once they learned the way it works, they may have said, "Hey that's >>> cool! I'm gonna use that from now on!" >>> >>> In other words, you seem to be talking about removing a feature that is >>> liked by *a lot* people, based on some unsubstantiated reports of user >>> error that may or may not have been totally unsubstantial. >>> >>> I don't want new programmers to be confused, either, but the "where" >>> clause is such a basic programming construct - the keyword is new, but the >>> idea itself is as old as programming - that I don't mind expecting new >>> programmers to learn how to use it. The learning curve should be incredibly >>> short - it is nothing more than a filter operation. >>> >>> There's something else here that is really important to me, though I >>> don't know how others feel about it. >>> >>> Using the guard...continue approach that you are promoting is a code >>> smell. It puts control-flow logic inside the for-in loop. That is something >>> I have always tried to avoid. I know that the language allows for it, but I >>> believe it is bad programming practice. In fact, if you get rid of the >>> `where` keyword, I'm still not going to use guard...continue. I'll just >>> filter the collection first and then loop it. >>> >> >> This is quite the statement. It sounds like you'd be for the elimination >> of `continue`? >> >> >>> >>> It is a code smell for the same reason that messing with the index >>> inside a for;; loop was a code smell. I was always taught never to do this: >>> >>> for var i = 0; i < array.count, i++ { >>> if iWantThisToLoopAnExtraTime { >>> i-- >>> } >>> } >>> >>> Why? Because code like that is confusing. It becomes difficult to know >>> how many times the loop will execute, what the looping logic is, etc. Sure, >>> I might get away with it most of the time, but it is bad practice and there >>> is always a better way to do what you want to do. The only thing that keeps >>> you from the better way is laziness. >>> >>> The same is true (albeit to a lesser degree) for the guard...continue. >>> It may not be as extreme, but it is still a code smell. It divides the >>> control-flow logic into two parts - one outside the loop, and one inside >>> the loop, and it suddenly becomes twice as easy to miss something. >>> >>> Using for-in-where, all of the control-flow logic is on one single line, >>> and once it is known that "where" operates as a filter operation, it all >>> works together in a single, harmonious statement that declares exactly what >>> is going to happen in a way that is totally unambiguous. >>> >>> So by getting rid of the "where" clause, I believe that you are actually >>> encouraging bad programming practice. Instead of encouraging the new user >>> to learn this very simple construct that will ultimately make their code >>> safer and more expressive without dividing their control-flow logic >>> unnecessarily into two separate parts, you are encouraging them to just "do >>> what they know". I think that is terrible, and you are doing them a >>> disservice. >>> >>> And from a personal standpoint, you are telling me that I have to write >>> smelly code, even though there is this perfectly good non-smelly option >>> sitting right there, because you don't want someone else to have to learn >>> something. >>> >>> On Mon, Jun 13, 2016 at 5:29 AM Xiaodi Wu <xiaodi...@gmail.com> wrote: >>> >>>> I think this discussion has made it pretty plain that what is claimed >>>> to be 'so useful' is barely ever used. Moreover, it provides no independent >>>> uses. The point of these pitches is to sound out arguments, not, as far as >>>> I was aware, to take a vote. >>>> >>>> On Mon, Jun 13, 2016 at 1:54 AM Jose Cheyo Jimenez <ch...@masters3d.com> >>>> wrote: >>>> >>>>> --1 >>>>> >>>>> I think it would be a waste of the community's time to do a formal >>>>> review when only two people are in favor of this removal. >>>>> >>>>> 'for in where' is so useful especially since we don't have for;;; >>>>> loops anymore. I'd say leave this alone; the majority doesn't want this >>>>> changed. >>>>> >>>>> >>>>> >>>>> On Jun 10, 2016, at 10:17 AM, Xiaodi Wu via swift-evolution < >>>>> swift-evolution@swift.org> wrote: >>>>> >>>>> I think this idea--if you don't like it, then you don't have to use >>>>> it--is indicative of a key worry here: it's inessential to the language >>>>> and >>>>> promotes dialects wherein certain people use it and others wherein they >>>>> don't. This is an anti-goal. >>>>> >>>>> On Fri, Jun 10, 2016 at 12:10 let var go <letva...@gmail.com> wrote: >>>>> >>>>> Leave it in! >>>>>> >>>>>> It's a great little tool. I don't use it very often, but when I do it >>>>>> is because I've decided that in the context of that piece of code it does >>>>>> exactly what I want it to do with the maximum amount of clarity. >>>>>> >>>>>> If you don't like it, then don't use it, but I can't see how it >>>>>> detracts from the language at all. >>>>>> >>>>>> The *only* argument that I have heard for removing it is that some >>>>>> people don't immediately intuit how to use it. I didn't have any trouble >>>>>> with it at all. It follows one of the most basic programming patterns >>>>>> ever: >>>>>> "For all x in X, if predicate P is true, do something." The use of the >>>>>> keyword "where" makes perfect sense in that context, and when I read it >>>>>> out >>>>>> loud, it sounds natural: "For all x in X where P, do something." That is >>>>>> an >>>>>> elegant, succinct, and clear way of stating exactly what I want my >>>>>> program >>>>>> to do. >>>>>> >>>>>> I don't doubt that it has caused some confusion for some people, but >>>>>> I'm not sold that that is a good enough reason to get rid of it. It seems >>>>>> strange to get rid of a tool because not everyone understands how to use >>>>>> it >>>>>> immediately, without ever having to ask a single question. As long as its >>>>>> not a dangerous tool (and it isn't), then keep it in the workshop for >>>>>> those >>>>>> times when it comes in handy. And even if there is some initial >>>>>> confusion, >>>>>> it doesn't sound like it lasted that long. It's more like, "Does this >>>>>> work >>>>>> like X, or does this work like Y? Let's see...oh, it works like X. Ok." >>>>>> That's the entire learning curve...about 5 seconds of curiosity followed >>>>>> by >>>>>> the blissful feeling of resolution. >>>>>> >>>>>> On Fri, Jun 10, 2016 at 9:32 AM Xiaodi Wu via swift-evolution < >>>>>> swift-evolution@swift.org> wrote: >>>>>> >>>>> On Fri, Jun 10, 2016 at 11:23 AM, Sean Heber via swift-evolution < >>>>>>> swift-evolution@swift.org> wrote: >>>>>>> >>>>>> > And to follow-up to myself once again, I went to my "Cool 3rd Party >>>>>>>> Swift Repos" folder and did the same search. Among the 15 repos in that >>>>>>>> folder, a joint search returned about 650 hits on for-in (again with >>>>>>>> some >>>>>>>> false positives) and not a single for-in-while use. >>>>>>>> >>>>>>>> Weird. My own Swift projects (not on Github :P) use “where” all the >>>>>>>> time with for loops. I really like it and think it reads *and* writes >>>>>>>> far >>>>>>>> better as well as makes for nicer one-liners. In one project, by rough >>>>>>>> count, I have about 20 that use “where” vs. 40 in that same project not >>>>>>>> using “where”. >>>>>>>> >>>>>>>> In another smaller test project, there are only 10 for loops, but >>>>>>>> even so one still managed to use where. >>>>>>>> >>>>>>>> Not a lot of data without looking at even more projects, I admit, >>>>>>>> but this seems to suggest that the usage of “where” is going to be very >>>>>>>> developer-dependent. Perhaps there’s some factor of prior background at >>>>>>>> work here? (I’ve done a lot of SQL in another life, for example.) >>>>>>>> >>>>>>> That is worrying if true, because it suggests that it's enabling >>>>>>> 'dialects' of Swift, an explicit anti-goal of the language. >>>>>>> >>>>>> >>>>>>>> I feel like “where” is a more declarative construct and that we >>>>>>>> should be encouraging that way of thinking in general. When using it, >>>>>>>> it >>>>>>>> feels like “magic” for some reason - even though there’s nothing >>>>>>>> special >>>>>>>> about it. It feels like I’ve made the language work *for me* a little >>>>>>>> bit >>>>>>>> rather than me having to contort my solution to the will of the >>>>>>>> language. >>>>>>>> This may be highly subjective. >>>>>>>> >>>>>>>> l8r >>>>>>>> Sean >>>>>>>> >>>>>>> _______________________________________________ >>>>>>>> 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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