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Re: Explanation of do: separatedBy: keyword message

by Rene Paul Mages (ramix)

Le 19/09/2025 Ã 20:47, stephane ducasse a Ã©critÂ : > Hello Rene Paul > > compare > > | res | > res := OrderedCollection new. > #($a $b $c) do: [:aChar | res add: aChar]. > res > > an OrderedCollection($a $b $c) > > | res | > res := OrderedCollection new. > #($a $b $c) do: [:aChar | res add: aChar; add: $,]. > res > > an OrderedCollection($a $, $b $, $c $,) > > > and > > | res | > res := OrderedCollection new. > #($a $b $c) do: [:aChar | res add: aChar] separatedBy: [res add: $,]. > res > > an OrderedCollection($a $, $b $, $c) These comparisons are very enlightening. Thank you very much Stephane. -- All the best Rene Paul Mages (ramix) GnuPG key : 0x9840A6F7 https://sites.google.com/view/les-logiciels-libres/pharo https://twitter.com/RenePaulMages

Sept. 19, 2025

Re: Explanation of do: separatedBy: keyword message

by stephane ducasse

Hello Rene Paul compare | res | res := OrderedCollection new. #($a $b $c) do: [:aChar | res add: aChar]. res an OrderedCollection($a $b $c) | res | res := OrderedCollection new. #($a $b $c) do: [:aChar | res add: aChar; add: $,]. res an OrderedCollection($a $, $b $, $c $,) and | res | res := OrderedCollection new. #($a $b $c) do: [:aChar | res add: aChar] separatedBy: [res add: $,]. res an OrderedCollection($a $, $b $, $c) > On 18 Sep 2025, at 02:59, Rene Paul Mages (ramix) via Pharo-users <pharo-users(a)lists.pharo.org> wrote: > > > > Le 18/09/2025 Ã 01:35, Rene Paul Mages (ramix) via Pharo-users a Ã©crit : >> Hello, >> Please give me a hint to understand the "do: separatedBy:" keyword message used in ProfStef tutorial : >> i) in Pharo version 12 : >> https://ramix.org/pharo/ProfStef/iterators23.png >> ii) in Pharo version 13 : >> https://ramix.org/pharo/ProfStef/iterators25.png > > I am using the FINDER to search do:separatedBy: > > and also the BROWSER ( Method: Collection>>do:separatedBy: ) > > https://ramix.org/pharo/ProfStef/MethodCollection.png > > but I don't understand the explanations. > > Nota Bene : > > I am rereading the chapter 9 (Collections) of Pharo_By_Example : > > https://scg.unibe.ch/download/pharobyexample/PBE1-2010-02-01.pdf > > -- > Thanks for your help. > Rene Paul Mages (ramix) GnuPG key : 0x9840A6F7 > https://sites.google.com/view/les-logiciels-libres/pharo > https://twitter.com/RenePaulMages StÃ©phane Ducasse http://stephane.ducasse.free.fr 06 30 93 66 73 "If you knew today was your last day on earth, what would you do differently? ....ESPECIALLY if, by doing something different, today might not be your last day on earth.â Calvin & Hobbes

Sept. 19, 2025

Re: Explanation of do: separatedBy: keyword message

by stephane ducasse

Hi tim Rene Paul is long time follower of Pharo. He is now a retired mathematician and this is nice to see him coding in Pharo :) S > On 18 Sep 2025, at 09:49, Tim Mackinnon via Pharo-users <pharo-users(a)lists.pharo.org> wrote: > > Hi - is this a homework question? While anyone here can tell you what it does - its probably more helpful to you to work through it and properly understand it. > > You haven't shown what the output is when you try it - which will give you a clue. Equally - in Smalltalk, the names of selectors like: #do:separatedBy: convey meaning (which is why we like to use good names, that hint at what parameters do). Finally - have you looked at the implementation of the method? The nice thing about Smalltalk is that there is very little magic - you can see the code that runs for operations - including things like #ifTrue: . Why don't you position your cursor on #do: and press ctrl-m (or cmd-m - for show iMplementors - its also in the context menu). This will let you see the code and you should be able to work it out. For fun - try doing the same for: 3 = 3 ifTrue: [ 1 + 1]. Finally - its also worth understanding [1+1] + 1 (and why it gives an error) whereas: [1+1] value + 1 dosn't. > > Hope this helps. > > Tim > > On Thu, 18 Sep 2025, at 12:35 AM, Rene Paul Mages (ramix) via Pharo-users wrote: >> Hello, >> >> Please give me a hint to understand the "do: separatedBy:" keyword >> message used in ProfStef tutorial : >> >> i) in Pharo version 12 : >> >> https://ramix.org/pharo/ProfStef/iterators23.png >> >> ii) in Pharo version 13 : >> >> https://ramix.org/pharo/ProfStef/iterators25.png >> >> -- >> Thanks for your help. >> Rene Paul Mages (ramix) GnuPG key : 0x9840A6F7 >> https://sites.google.com/view/les-logiciels-libres/pharo >> https://twitter.com/RenePaulMages StÃ©phane Ducasse http://stephane.ducasse.free.fr 06 30 93 66 73 "If you knew today was your last day on earth, what would you do differently? ....ESPECIALLY if, by doing something different, today might not be your last day on earth.â Calvin & Hobbes

Sept. 19, 2025

Re: Creation of a class help

by Cyril FERLICOT-DELBECQUE

Hi, Object and ProtocObject are not packages but classes. You can find them in multiple ways: - Using the Spotter (CMD/Ctrl + space) - Using the Finder (Browse -> Finder) - Using the class finder (In the Code Browser you can right click on a package and select "Find class" - By typing the name of the class in a Playground and doing CMD/CTRL + b to browse the class Those classes are in the Kernel package -- Cyril Ferlicot-Delbecque https://ferlicot.fr On Friday, September 19th, 2025 at 3:36 PM, RenePaulMages via Pharo-users <pharo-users(a)lists.pharo.org> wrote: > Hello, > > I am restuding the chapter 5 ( Developing a simple counter ) of > " Learning OOP " book : > > http://files.pharo.org/books-pdfs/learning-oop/2018-04-01-LearningOOP.pdf > > In the browser of Pharo version 13 I can't find neither the Object > package nor the ProtoObject package. > > -- > Thanks for your help > Rene Paul Mages (ramix) GnuPG : 0x9840A6F7 > https://wiki.linux-azur.org/?PagePHARO > https://renemages.wordpress.com/smalltalk/pharo > https://sites.google.com/view/les-logiciels-libres/pharo

Sept. 19, 2025

Creation of a class help

by RenePaulMages

Hello, I am restuding the chapter 5 ( Developing a simple counter ) of " Learning OOP " book : http://files.pharo.org/books-pdfs/learning-oop/2018-04-01-LearningOOP.pdf In the browser of Pharo version 13 I can't find neither the Object package nor the ProtoObject package. -- Thanks for your help Rene Paul Mages (ramix) GnuPG : 0x9840A6F7 https://wiki.linux-azur.org/?PagePHARO https://renemages.wordpress.com/smalltalk/pharo https://sites.google.com/view/les-logiciels-libres/pharo

Sept. 19, 2025

Re: Explanation of do: separatedBy: keyword message

by RenePaulMages

Le 18/09/2025 Ã 10:30, Richard O'Keefe via Pharo-users a Ã©critÂ : Thank you Richard and Tim for your help. > The ANSI Smalltalk standard has this to say: > do: operation separatedBy: separator > For each element of the receiver, operation is evaluated with the element > as the parameter. > Before evaluating operation the second and subsequent times, evaluate > separator. > Separator is not evaluated if there are no elements or after the last > element. I understand now. > We could implement this in Collection like so: > > do: doBlock separatedBy: separatorBlock > |started| > started := false. > self do: [:each | > started ifTrue: [separator value] ifFalse: [started := true]. > doBlock value: each]. > > You can look at the actual source code by typing > do:separatedBy: > in a Playground (Workspace) and then typing Ctrl-M (show iMplementors). Ok. > The idea is simple enough: aCollection do: aBlock separatedBy: > separatorBlock > invokes (aBlock value: x1) ... (aBlock value: xn) where x1 ... xn are the > elements of aCollection, but *between* each pair of calls to aBlock there is > an invocation of (separatorBlock value). Now I understand the idea. > A good thing to do after you have looked at the implementation(s) is to look > at how it's used. Type do:separatedBy: > into a Playground and type Ctrl-N (show seNders). It's almost always > printing or concatenating with a separator. > And that is EXACTLY what is happening in the ProfStef tutorial you show. Perfect. > Let's take a simple example. > Suppose you have a string 'abcd'. > If you want to write /a/b/c/d > string do: [:each | aStream nextPut: $/; nextPut: each]. > If you want to write a/b/c/d/ > string do: [:each | aStream nextPut: each; nextPut: $/]. > So far so good, there are exactly as many / writes as there are element > writes, > so they can go in the same block. But if you want to write a/b/c/d what do > you do? > Now you have one FEWER separator than elements. > > string do: [:each | aStream nextPut: each] separatedBy: [aStream nextPut:$/] > does the trick. You could of course bodge something together yourself, > BUT #do:separatedBy: is a well known idiom so it is much easier for people > to understand. It is clear now. > > Another approach would have been > > Collection >>doFirst: firstBlock thenDo: otherBLock > |started| > started := false. > self do: [:each | > started ifTrue: [otherBlock value: each] ifFalse: [firstBlock value: > each. started := true]]. > > and then we could write > > aString doFirst: [:first | aStream nextPut: first] thenDo: [:each | > aStream nextPut: $/; nextPut: each] > > but that would involve code duplication, so we use #do:separatedBy: instead. Your explanation is _very_ complete. -- Thanks for your help. Rene Paul Mages (ramix) GnuPG : 0x9840A6F7 https://renemages.wordpress.com/smalltalk/pharo https://sites.google.com/view/les-logiciels-libres/pharo https://twitter.com/RenePaulMages

Sept. 18, 2025

Re: Explanation of do: separatedBy: keyword message

by Richard O'Keefe

The ANSI Smalltalk standard has this to say: do: operation separatedBy: separator For each element of the receiver, operation is evaluated with the element as the parameter. Before evaluating operation the second and subsequent times, evaluate separator. Separator is not evaluated if there are no elements or after the last element. We could implement this in Collection like so: do: doBlock separatedBy: separatorBlock |started| started := false. self do: [:each | started ifTrue: [separator value] ifFalse: [started := true]. doBlock value: each]. You can look at the actual source code by typing do:separatedBy: in a Playground (Workspace) and then typing Ctrl-M (show iMplementors). The idea is simple enough: aCollection do: aBlock separatedBy: separatorBlock invokes (aBlock value: x1) ... (aBlock value: xn) where x1 ... xn are the elements of aCollection, but *between* each pair of calls to aBlock there is an invocation of (separatorBlock value). A good thing to do after you have looked at the implementation(s) is to look at how it's used. Type do:separatedBy: into a Playground and type Ctrl-N (show seNders). It's almost always printing or concatenating with a separator. And that is EXACTLY what is happening in the ProfStef tutorial you show. Let's take a simple example. Suppose you have a string 'abcd'. If you want to write /a/b/c/d string do: [:each | aStream nextPut: $/; nextPut: each]. If you want to write a/b/c/d/ string do: [:each | aStream nextPut: each; nextPut: $/]. So far so good, there are exactly as many / writes as there are element writes, so they can go in the same block. But if you want to write a/b/c/d what do you do? Now you have one FEWER separator than elements. string do: [:each | aStream nextPut: each] separatedBy: [aStream nextPut: $/] does the trick. You could of course bodge something together yourself, BUT #do:separatedBy: is a well known idiom so it is much easier for people to understand. Another approach would have been Collection >> doFirst: firstBlock thenDo: otherBLock |started| started := false. self do: [:each | started ifTrue: [otherBlock value: each] ifFalse: [firstBlock value: each. started := true]]. and then we could write aString doFirst: [:first | aStream nextPut: first] thenDo: [:each | aStream nextPut: $/; nextPut: each] but that would involve code duplication, so we use #do:separatedBy: instead. On Thu, 18 Sep 2025 at 11:35â¯AM, Rene Paul Mages (ramix) via Pharo-users < pharo-users(a)lists.pharo.org> wrote: > Hello, > > Please give me a hint to understand the "do: separatedBy:" keyword > message used in ProfStef tutorial : > > i) in Pharo version 12 : > > https://ramix.org/pharo/ProfStef/iterators23.png > > ii) in Pharo version 13 : > > https://ramix.org/pharo/ProfStef/iterators25.png > > -- > Thanks for your help. > Rene Paul Mages (ramix) GnuPG key : 0x9840A6F7 > https://sites.google.com/view/les-logiciels-libres/pharo > https://twitter.com/RenePaulMages > > >

Sept. 18, 2025

Re: Explanation of do: separatedBy: keyword message

by Tim Mackinnon

Hi - is this a homework question? While anyone here can tell you what it does - its probably more helpful to you to work through it and properly understand it. You haven't shown what the output is when you try it - which will give you a clue. Equally - in Smalltalk, the names of selectors like: #do:separatedBy: convey meaning (which is why we like to use good names, that hint at what parameters do). Finally - have you looked at the implementation of the method? The nice thing about Smalltalk is that there is very little magic - you can see the code that runs for operations - including things like #ifTrue: . Why don't you position your cursor on #do: and press ctrl-m (or cmd-m - for show iMplementors - its also in the context menu). This will let you see the code and you should be able to work it out. For fun - try doing the same for: 3 = 3 ifTrue: [ 1 + 1]. Finally - its also worth understanding [1+1] + 1 (and why it gives an error) whereas: [1+1] value + 1 dosn't. Hope this helps. Tim On Thu, 18 Sep 2025, at 12:35 AM, Rene Paul Mages (ramix) via Pharo-users wrote: > Hello, > > Please give me a hint to understand the "do: separatedBy:" keyword > message used in ProfStef tutorial : > > i) in Pharo version 12 : > > https://ramix.org/pharo/ProfStef/iterators23.png > > ii) in Pharo version 13 : > > https://ramix.org/pharo/ProfStef/iterators25.png > > -- > Thanks for your help. > Rene Paul Mages (ramix) GnuPG key : 0x9840A6F7 > https://sites.google.com/view/les-logiciels-libres/pharo > https://twitter.com/RenePaulMages

Sept. 18, 2025

Re: Explanation of do: separatedBy: keyword message

by Rene Paul Mages (ramix)

Le 18/09/2025 Ã 01:35, Rene Paul Mages (ramix) via Pharo-users a Ã©critÂ : > Hello, > > Please give me a hint to understand the "do: separatedBy:" keyword > message used in ProfStef tutorial : > > Â i) in Pharo version 12 : > > Â Â https://ramix.org/pharo/ProfStef/iterators23.png > > ii) in Pharo version 13 : > > Â Â https://ramix.org/pharo/ProfStef/iterators25.png I am using the FINDER to search do:separatedBy: and also the BROWSER ( Method: Collection>>do:separatedBy: ) https://ramix.org/pharo/ProfStef/MethodCollection.png but I don't understand the explanations. Nota Bene : I am rereading the chapter 9 (Collections) of Pharo_By_Example : https://scg.unibe.ch/download/pharobyexample/PBE1-2010-02-01.pdf -- Thanks for your help. Rene Paul Mages (ramix) GnuPG key : 0x9840A6F7 https://sites.google.com/view/les-logiciels-libres/pharo https://twitter.com/RenePaulMages

Sept. 18, 2025

Explanation of do: separatedBy: keyword message

by Rene Paul Mages (ramix)

Hello, Please give me a hint to understand the "do: separatedBy:" keyword message used in ProfStef tutorial : i) in Pharo version 12 : https://ramix.org/pharo/ProfStef/iterators23.png ii) in Pharo version 13 : https://ramix.org/pharo/ProfStef/iterators25.png -- Thanks for your help. Rene Paul Mages (ramix) GnuPG key : 0x9840A6F7 https://sites.google.com/view/les-logiciels-libres/pharo https://twitter.com/RenePaulMages

Sept. 17, 2025