January 2020 - Pharo-users - lists.pharo.org

Re: [Pharo-users] Prof Stef questions

by tbrunz

Your problem has to do with understanding how the 'ifTrue:ifFalse:' message is evaluated. This expression 1 < 2 ifTrue: [100] ifFalse: [42]. evaluates to '100'; it does not evaluate to "a block that will return 100 when evaluated". The blocks that make up the arguments to 'ifTrue:ifFalse:' will be selectively evaluated at run-time, by the receiver of the message, when the receiver makes the determination of which block to evaluate. In your modification, you mistakenly assume that one of the two block arguments will selected and returned verbatim (to be evaluated later in another context), but this is not how it works. When you write 'ifTrue: [:x|x+1]', and the receiver of the message is 'True', then 'True' will attempt to evaluate your block argument. But your block argument requires an argument itself, which is missing -- Hence the error that results. What you want is an "ifTrue:' argument block that will itself evaluate to another block that you can assign to 'a'. The fix is simple: Just enclose it in another set of '[ ]' like so: |a| a := 1 < 2 ifTrue: [ [:x|x+1] ] ifFalse: [42]. a value: 20. And the result will be '21', as intended. -Ted -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

Jan. 5, 2020

Re: [Pharo-users] Prof Stef questions

by Richard Sargent

On Sun, Jan 5, 2020 at 8:08 AM xap <xap(a)router.33mail.com> wrote: > hi, I'm starting out w/ pharo (as my first smalltalk-ish language). am on > Windows 7 professional; downloaded 64-bit, pharo 8 64-bit development; then > downgraded to pharo 7, 32-bit stable. > I went through Prof Stef, and find 1 place of unexpected behavior: > > Prof Stef/Conditionals: > > "no surprises, prints 100" > 1 < 2 > ifTrue: [100] > ifFalse: [42]. > > "i added a, as below, and get an error -- i would've expected a to refer to > the block, and to be evaluable later, similar to the just prior example in > ProfStef/Block assignation" > > |a| > a := 1 < 2 > ifTrue: [:x|x+1] > ifFalse: [42]. > a value: 20. > > What am I missing, pls? > It is always a good idea to describe in detail what behaviour you did observe. "get an error" is the same as "it didn't work". It turns out that you are NOT assigning a Block to the temporary variable a. You are *evaluating* one of the two blocks in the #ifTrue:ifFalse: expression. Remember that the arguments to #ifTrue: and #ifFalse: are blocks that will be evaluated if the receiver is the correct Boolean. In this case, before there is a value to assign to a, the #ifTrue: block gets evaluated (since 1 is < 2). But, it is a one argument block and there is no value available for that argument. You should have been given the opportunity to open the debugger when the error occurred, and you would have been able to see the stack and recognize that the error occurred in the execution of the #ifTrue:ifFalse: method. I won't give you the answer at this point, as you should be able to figure it out now. Just remember that the expression essentially looks like aBoolean ifTrue: [anExpression] ifFalse: [anotherExpression] > > > > -- > Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html > >

Jan. 5, 2020

Re: [Pharo-users] Prof Stef questions

by Santiago Dandois

Hi, I haven't run your code, but I guess that the validation of the number of arguments of the block is failing. The block [ 42 ] is a block with zero arguments, but when you do a value: 20, you are calling it with one argument. So it fails. Happy Coding! Santiago Dandois El dom., 5 ene. 2020 a las 13:08, xap (<xap(a)router.33mail.com>) escribiÃ³: > hi, I'm starting out w/ pharo (as my first smalltalk-ish language). am on > Windows 7 professional; downloaded 64-bit, pharo 8 64-bit development; then > downgraded to pharo 7, 32-bit stable. > I went through Prof Stef, and find 1 place of unexpected behavior: > > Prof Stef/Conditionals: > > "no surprises, prints 100" > 1 < 2 > ifTrue: [100] > ifFalse: [42]. > > "i added a, as below, and get an error -- i would've expected a to refer to > the block, and to be evaluable later, similar to the just prior example in > ProfStef/Block assignation" > > |a| > a := 1 < 2 > ifTrue: [:x|x+1] > ifFalse: [42]. > a value: 20. > > What am I missing, pls? > > > > > -- > Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html > >

Jan. 5, 2020

Prof Stef questions

by xap

hi, I'm starting out w/ pharo (as my first smalltalk-ish language). am on Windows 7 professional; downloaded 64-bit, pharo 8 64-bit development; then downgraded to pharo 7, 32-bit stable. I went through Prof Stef, and find 1 place of unexpected behavior: Prof Stef/Conditionals: "no surprises, prints 100" 1 < 2 ifTrue: [100] ifFalse: [42]. "i added a, as below, and get an error -- i would've expected a to refer to the block, and to be evaluable later, similar to the just prior example in ProfStef/Block assignation" |a| a := 1 < 2 ifTrue: [:x|x+1] ifFalse: [42]. a value: 20. What am I missing, pls? -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

Jan. 5, 2020

Re: [Pharo-users] How can we celebrate the 50th anniversary of Smalltalk?

by James Foster

> On Jan 5, 2020, at 7:39 AM, ponyatov <dponyatov(a)gmail.com> wrote: > > The best tribute to 50th anniversary will be the implementation of > distributed multi-user VM. How would that be different from GemStone?

Jan. 5, 2020

Re: [Pharo-users] How can we celebrate the 50th anniversary of Smalltalk?

by ponyatov

The best tribute to 50th anniversary will be the implementation of distributed multi-user VM. -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

Jan. 5, 2020

Re: [Pharo-users] is this better regarding naming thigs

by Sven Van Caekenberghe

> On 5 Jan 2020, at 15:06, Roelof Wobben via Pharo-users <pharo-users(a)lists.pharo.org> wrote: > > > From: Roelof Wobben <r.wobben(a)home.nl> > Subject: is this better regarding naming thigs > Date: 5 January 2020 at 15:06:18 GMT+1 > To: Any question about pharo is welcome <pharo-users(a)lists.pharo.org> > > > Hello > > In a earlier question I get a remark to think better about naming things. > Now I did a challene where I have to find anagrams of a given word in a collection, > > So I did this : > > findAnagramsCandidates: aCollection subject: aWord > | charBag | > charBag := aWord asLowercase asBag. > ^ aCollection > reject: > [ :word | (word sameAs: aWord) or: [ word asLowercase asBag ~= charBag ] ] > > > is my naming here better or can i improved and if so how ? It is good. Possible alternatives: aCollectionOfWords instead of aCollection, I would even dare to use words/wordsCollection and word, since I am not a big fan of the 'a' and 'an' prefixes. Also the argument to the reject block is often called each or eachWord, but this is more of a tradition, word is OK too (but it would then conflict with naming the argument word). > Regards, > > Roelof > > > >

Jan. 5, 2020

Re: [Pharo-users] why is my css not found in a seaside project

by Sven Van Caekenberghe

> On 5 Jan 2020, at 14:46, Roelof Wobben via Pharo-users <pharo-users(a)lists.pharo.org> wrote: > > > From: Roelof Wobben <r.wobben(a)home.nl> > Subject: Re: [Pharo-users] why is my css not found in a seaside project > Date: 5 January 2020 at 14:46:24 GMT+1 > To: pharo-users(a)lists.pharo.org > > > I think I found the answer myself > > when I put this in the RootComponent > > updateRoot: anHtmlRoot > super updateRoot: anHtmlRoot. > anHtmlRoot stylesheet url: (PaintingLibrary urlOf: #mainCss) > > and this on the class side of the RootComponent > > > initialize > | app | > app := WAAdmin > register: #stRootComponent > asApplicationAt: 'Paintings2'. > app addLibrary: PaintingLibrary > > > then I see some css. The page looks not what I expect but that can be changed. > > So does the code I have now on my github page well or do I use the components still the wrong way ? What you write above is correct, it is what I meant. Good that you figured it out ! > Roelof > > > > Op 5-1-2020 om 12:48 schreef Roelof Wobben: >> Op 5-1-2020 om 11:36 schreef Roelof Wobben via Pharo-users: >> >> hmm, >> >> It looks like I had to do it like this : https://github.com/RoelofWobben/paintings >> for registering the project but I see then that the rootcomponent is not changed and that still the css is not found or used. >> >> >> So please help. >> >> Roelof >> > > > >

Jan. 5, 2020

Re: [Pharo-users] How can we celebrate the 50th anniversary of Smalltalk?

by HernÃ¡n Morales Durand

Hi there, Maybe people is thinking about a great celebration idea :) Cheers, HernÃ¡n El dom., 5 ene. 2020 a las 1:07, horrido (<horrido.hobbies(a)gmail.com>) escribiÃ³: > horrido wrote > > > https://medium.com/@richardeng/how-can-we-celebrate-the-50th-anniversary-of… > > Amazingly, no one has any suggestions! I'm afraid the 50th anniversary will > pass very quietly. > > > > -- > Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html > >

Jan. 5, 2020

is this better regarding naming thigs

by Roelof Wobben

Hello In a earlier question I get a remark to think better about naming things. Now I didÂ a challene where I have to find anagrams of a given word in a collection, So I did this : findAnagramsCandidates: aCollection subject: aWord Â Â Â | charBag | Â Â Â charBag := aWord asLowercase asBag. Â Â Â ^ aCollection Â Â Â Â Â Â reject: Â Â Â Â Â Â Â Â Â [ :word | (word sameAs: aWord) or: [ word asLowercase asBag ~= charBag ] ] is my naming here better or can i improved and if so how ? Regards, Roelof

Jan. 5, 2020