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

Re: [Pharo-users] can I make this so the vm would not be not responsibe when running the tests
by Richard O'Keefe Jan. 7, 2020

Jan. 7, 2020

Time microsecondsToRun: [ |n| n := (2 raisedToInteger: 8 * 8) - 1. Transcript nextPutAll: 'The number of grains on an 8x8 chessboard is '; print: n; cr; endEntry]. <PRINT-IT> On my laptop, this reports 194 microseconds. Why would you use recursion, anyway? Time microsecondsToRun: [ |n| n := (1 to: 8 * 8) inject: 0 into: [:acc :each | acc+acc+1]. Transcript nextPutAll: 'The number of grains on an 8x8 chessboard is '; print: n; cr; endEntry]. <PRINT-IT> On the same laptop, this reports 118 microseconds. One of the lessons of 'functional' languages, promptly adopted by Smalltalk, is to encapsulate control structures into reusable methods, such as #inject:into:, more commonly known as `foldl` in functional languages. It's then none of my business whether such a method works by recursion, iteration, or gangs of otherwise seasonally unemployed Christmas elves. In my own Smalltalk library, (GeometricSeries new: 64 from: 1 byFactor: 2) sum only takes 15 microseconds. I do note that you are calling validateInput repeatedly. Why? On Sun, 5 Jan 2020 at 07:41, Roelof Wobben via Pharo-users <pharo-users(a)lists.pharo.org> wrote: > > Oke, > > So I can better not use recursion for this problem if I understand you well, Richard. > > Roelof > > > > Op 4-1-2020 om 19:02 schreef Richard Sargent: > > On Sat, Jan 4, 2020 at 9:47 AM Roelof Wobben via Pharo-users <pharo-users(a)lists.pharo.org> wrote: >> >> Hello, >> >> For a exercism challenge I need to calculate the total grains on a >> chessboard. >> So I did : >> >> atSquare: anInteger >> self validateInput: anInteger. >> ^ anInteger = 1 >> ifTrue: [ 1 ] >> ifFalse: [ 2 * (self atSquare: anInteger - 1) ] >> >> >> but when I run the tests , the vm seems to be not responsive for some 4 >> - 5 seconds. >> >> Is there a way I can use this code and take care that the vm stays >> responsive. > > > What do you want the VM to do in addition to calculating that sum while it is calculating that sum? > > > The best way to keep the VM responsive is to take a page from Gauss' notebook and pay attention to the numbers[1]. Let's consider the first four squares and extrapolate from there. > > In binary, the squares hold the following grains: 2r1, 2r10, r2100, and 2r1000. When we add them up, we get 2r1111. If we use Gauss' tricks, we can notice that 2r1111 is equal to 2r10000 - 1. So, the sum of the grains on the first 4 squares is 2^5 - 1. You can easily generalize that pattern, of course. Then your program can calculate the answer quickly. > > > [1] The story goes that Gauss' teacher was frustrated with his student's abilities and set him a challenge to occupy him for some time: sum the numbers from 1 through 100. Gauss immediately answered 5,050, much to his teacher's chagrin. > >> >> Regards, >> >> Roelof >> >> >

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Prof Stef questions
by xap Jan. 7, 2020

Jan. 7, 2020

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

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Re: [Pharo-users] [seaside] how can I now make the best work to display all the paiintings which are in the paintings collection
by Paul DeBruicker Jan. 6, 2020

Jan. 6, 2020

Hi Roelof, There is a seaside specific mailing list you could join here: http://lists.squeakfoundation.org/cgi-bin/mailman/listinfo/seaside I have Seaside loaded in an image and can't find the ListComponent class. IS that the correct name for the class you're using? If you post your question along with the code you are trying to the Seaside list someone will probably be able to help you. What you're describing sounds straightforward to implement. Good luck Paul Pharo Smalltalk Users mailing list wrote > Hello, > > Im a little bit further on my first project but now I fail to see how I > can use the ListComponent to display all the paintings that are in the > paintings collection on the Paintings class. > > Anyone who can give me hints on this ? > > Roelof -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

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Re: [Pharo-users] is this better regarding naming thigs
by xap Jan. 6, 2020

Jan. 6, 2020

Here's the permalink to Sven's response (in case it still isn't visible to you): http://forum.world.st/is-this-better-regarding-naming-thigs-tp5109389p51093… -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

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Re: [Pharo-users] is this better regarding naming thigs
by xap Jan. 6, 2020

Jan. 6, 2020

hi Roelof, i didn't mean to hijack your thread, sorry -- my question was directed at you, then kinda took on a life of its own. That said, Sven had/has responded to your op (original post), no? One additional change I would make: rename "findAnagramsCandidates" --> "findAnagrams" : it's shorter, and possibly more correct since what's returned are true anagrams rather than candidates-that-may-be-anagrams ? -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

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[seaside] how can I now make the best work to display all the paiintings which are in the paintings collection
by Roelof Wobben Jan. 5, 2020

Jan. 5, 2020

Hello, Im a little bit further on my first project but now I fail to see how I can use the ListComponent to display all the paintings that are in the paintings collection on the Paintings class. Anyone who can give me hints on this ? Roelof

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Re: [Pharo-users] is this better regarding naming thigs
by Sven Van Caekenberghe Jan. 5, 2020

Jan. 5, 2020

> 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 > > > >

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Re: [Pharo-users] why is my css not found in a seaside project
by Sven Van Caekenberghe Jan. 5, 2020

Jan. 5, 2020

> 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 >> > > > >

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is this better regarding naming thigs
by Roelof Wobben Jan. 5, 2020

Jan. 5, 2020

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

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Re: [Pharo-users] why is my css not found in a seaside project
by Roelof Wobben Jan. 5, 2020

Jan. 5, 2020

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

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