As many have described, I’ve seen this work reasonably well too - while I’ve seen the pvt prefix convention, I’ve also seen _name used to - which I felt was marginally better (it also means private methods get grouped at the top of the “all list” and not alphabetically in the middle’ish (but it’s a minor thing as browser tools can filter appropriately anyway, and to be honest, showing private at the bottom or in a separate place is better).
It is worth saying however - that lots if pvt methods can be a code smell - it may be better to move them to a separate “policy object” and then focus on better delegation options - which I believe is where Pharo is heading with variables as first class objects (and hopefully Marcus will cover in the U.K. Smalltalk Meetup this week). Too often we end up up with lots of sub classing and overriding and privatising - when there is a new object that could group all this stuff and the methods can be public in that delegate - while the delegate itself is a “private” object. I think this should be explored more actually. Tim > On 20 Aug 2021, at 11:19, Richard O'Keefe <rao...@gmail.com> wrote: > > One of the claimed benefits of object-oriented programming is ENCAPSULATION. > The idea is that one of the ways a language helps you is by making some errors > difficult or impossible to express. > One of the things you need to understand an object is its INVARIANT. > For example, astc's SortedCollection includes > > methods for: 'checking' > invariant > ^(opposite isNil or: [ > opposite isKindOf: DyadicBlock]) and: [ > super invariant and: [ > (sortBlock > ifNil: [(offset + 2 to: offset + size) allSatisfy: [:i | > (array at: i-1) <= (array at: i)]] > ifNotNil: [(sortBlock respondsTo: #value:value:) and: [ > [(offset + 2 to: offset + size) allSatisfy: [:i | > (sortBlock value: (array at: i-1) > value: (array at: i))]]]])]] > > Private methods are allowed to break the invariant. > Public methods are not. > > For example, consider reversing a SortedCollection. > Part of this changes the order of the elements, and can be > shared with OrderedCollection. Part of it swaps the arguments > of the sortBlock, and cannot be shared. > > methods for: 'rearranging' > pvtPrereverse > |t| > opposite > ifNil: [ > sortBlock ifNil: [sortBlock := Magnitude defaultSortBlock]. > t := sortBlock. > opposite := sortBlock. > sortBlock := [:x :y | t value: y value: x]] > ifNotNil: [ > t := sortBlock. > sortBlock := opposite. > opposite := t]. > > If this method could be called from "outside", it would certainly break > the invariant and leave the object in an unusable state. > > Now a style rule doesn't *quite* prevent this method being called by > another object. > It is necessary to make sure that #perform: and friends cannot break > encapsulation > either, and this astc does by simply not creating Selector objects for > private methods. > > Yes, it is a small increase in the complexity of the language, however > - you are not forced to write private methods > - if you run code that uses the pvt* convention in a Smalltalk that does > not use that convention, it works, it's just not safe any longer > - it is not an arbitrary addition to the language, it is a restriction that > makes programming *easier*. > > Let's look at one additional example. > Behavior>> > new > ^ self basicNew initialize > > This means that *any* object can forcibly reinitialize *any* object it can > reach at *any* time. In astc, it's > > new > "other checks" > ^self pvtNew pvtPostNew > > and an object cannot be reinitialised against its will. > > There is a long standing tradition of "program for the typical case and trust > the omniscient programmer to know what will probably work and what won't" > in Smalltalk. This is why in many Smalltalks > aCollection addAll: aCollection > or > aCollection removeAll: aCollection > can go insane for some common collections. And one *DOES* get away > with it most of the time. It's typically when someone else triest to use your > code and doesn't know the assumptions you didn't bother to write down > that things go wrong. It's obvious that Pharo has got to where it > amazingly well is without the "bondage and discipline" of, say, Ada or > Agda. But there is a *reason* why Pharo has lint checking on by default. > >> On Fri, 20 Aug 2021 at 00:59, Jesus Mari Aguirre <jmariagui...@gmail.com> >> wrote: >> >> Please keep Pharo simple, why do you need private methods...you can include >> then in a protocol named private...other language have it...yes...next >> addition will be namespaces...other...I don't know...at last we have Java >> >> El jue., 19 ago. 2021 9:00, Richard O'Keefe <rao...@gmail.com> escribió: >>> >>> Many years ago there was a proposal in the Squeak mailing list about >>> enforcing >>> a naming convention, "pvt", I implemented that in my Smalltalk system. The >>> compiler enforces the rule that pvt.[A-Z].* message can only be sent to >>> (self|super) (basicNew|basicNew: n|new|new: n|pvtNew: n)? >>> in a class method or >>> (self|super) ((class (new|new: n)|pvtSpeciesNew: n|pvtClone)? >>> in an instance method. >>> There are currently >>> 9412 public selectors >>> 793 pvt* selectors and >>> 23 private* selectors, >>> where the last group is methods that I *want* to be private in some sense >>> but >>> cannot do with this machinery. (For example, calling a "private" method on >>> another object known to be of the same class.) >>> >>> I think the evidence shows that this works well enough to be useful, even >>> if it >>> isn't quite as expressive as I'd like. And what *that* means is that >>> this can be >>> done with a style check, using the machinery Pharo already has for style >>> checks. >>> >>> >>> >>> On Wed, 18 Aug 2021 at 08:14, Craig Johnson <cr...@hivemind.net> wrote: >>>> >>>> Hi All, >>>> >>>> >>>> Just a newb off-the-wall question. >>>> >>>> Is there any good reason why we can't create a true private method in a >>>> Pharo class by putting that method inside an instance or class variable >>>> as a lambda (block). >>>> >>>> >>>> This would reduce one of my biggest bugbears with Pharo, namely the >>>> pollution of the global namespace with every single message name in the >>>> entire system. >>>> >>>> >>>> >>>> Craig
