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

Re: [Pharo-users] [ANN] XMLParserHTML moved to GitHub

by PBKResearch

It may be a quirk of how Pharo Playground works. It doesn't need local variable declarations - which is convenient - but putting them in can screw things up. Try your snippet again without the first line. Compare Torsten's code. HTH Peter Kenny -----Original Message----- From: Pharo-users <pharo-users-bounces(a)lists.pharo.org> On Behalf Of Torsten Bergmann Sent: 07 January 2020 07:47 To: pharo-users(a)lists.pharo.org Cc: pharo-users(a)lists.pharo.org Subject: Re: [Pharo-users] [ANN] XMLParserHTML moved to GitHub Works without a problem (Pharo 8 on Windows), see attached. So it looks like a local problem. Just check the debugger and compare to the squeak version where you run in trouble. Maybe the document could not be retrieved on your machine. Bye T. > Gesendet: Dienstag, 07. Januar 2020 um 04:42 Uhr > Von: "LawsonEnglish" <lenglish5(a)cox.net> > An: pharo-users(a)lists.pharo.org > Betreff: Re: [Pharo-users] [ANN] XMLParserHTML moved to GitHub > > Torsten Bergmann wrote > > Hi, > > > > > > You can load using > > > > Metacello new > > baseline: 'XMLParserHTML'; > > repository: 'github://pharo-contributions/XML-XMLParserHTML/src'; > > load. > > > > > > Bye > > T. > > Hi, > > I'm trying to use the sample code in the pharo screen scraping booklet > â > http://books.pharo.org/booklet-Scraping/pdf/2018-09-02-scrapingbook.pdf â but while everything appears to load, I'm getting an odd behavior from: > > /| ingredientsXML | > ingredientsXML := XMLHTMLParser parseURL: > 'https://ndb.nal.usda.gov/ndb/search/list?sort=ndb&ds=Standard+Reference'. > ingredientsXML inspect/ > > "#new was sent to nil" > > No matter what URL I use, I get the same message. > > I'm using Mac OS Catalina so I thought I might have some strange Mac > OS security issue (like it was quietly refusing to allow Pharo to > access the internet), but I tested with squeak and the old > > /html :=(HtmlParser parse: > 'https://ndb.nal.usda.gov/ndb/search/list?sort=ndb&ds=Standard+Reference' > asUrl retrieveContents content)/ > > and that returns actual html without any problems. > > > Suggestions? > > > Thanks. > > L > > > > > -- > Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html > >

Jan. 7, 2020

Re: [Pharo-users] [ANN] XMLParserHTML moved to GitHub

by Torsten Bergmann

Works without a problem (Pharo 8 on Windows), see attached. So it looks like a local problem. Just check the debugger and compare to the squeak version where you run in trouble. Maybe the document could not be retrieved on your machine. Bye T. > Gesendet: Dienstag, 07. Januar 2020 um 04:42 Uhr > Von: "LawsonEnglish" <lenglish5(a)cox.net> > An: pharo-users(a)lists.pharo.org > Betreff: Re: [Pharo-users] [ANN] XMLParserHTML moved to GitHub > > Torsten Bergmann wrote > > Hi, > > > > > > You can load using > > > > Metacello new > > baseline: 'XMLParserHTML'; > > repository: 'github://pharo-contributions/XML-XMLParserHTML/src'; > > load. > > > > > > Bye > > T. > > Hi, > > I'm trying to use the sample code in the pharo screen scraping booklet â > http://books.pharo.org/booklet-Scraping/pdf/2018-09-02-scrapingbook.pdf â > but while everything appears to load, I'm getting an odd behavior from: > > /| ingredientsXML | > ingredientsXML := XMLHTMLParser parseURL: > 'https://ndb.nal.usda.gov/ndb/search/list?sort=ndb&ds=Standard+Reference'. > ingredientsXML inspect/ > > "#new was sent to nil" > > No matter what URL I use, I get the same message. > > I'm using Mac OS Catalina so I thought I might have some strange Mac OS > security issue (like it was quietly refusing to allow Pharo to access the > internet), but I tested with squeak and the old > > /html :=(HtmlParser parse: > 'https://ndb.nal.usda.gov/ndb/search/list?sort=ndb&ds=Standard+Reference' > asUrl retrieveContents content)/ > > and that returns actual html without any problems. > > > Suggestions? > > > Thanks. > > L > > > > > -- > Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html > >

Jan. 7, 2020

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

by xap

richard, fwiw Roeloff mentioned earlier that the message-name was provided by the exercise set he's following, and isn't of his invention: http://forum.world.st/is-this-better-regarding-naming-thigs-tp5109389p51094… . he sh/could fwd your note/s to the course-author ;) -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

Jan. 7, 2020

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

by Richard O'Keefe

When I wrote "is not good English", I meant that "findAnagramsCandidates" sounds *horrible* to this native speaker of English. "findCandidateAnagrams" works. On Tue, 7 Jan 2020 at 18:12, Richard O'Keefe <raoknz(a)gmail.com> wrote: > > What is the receiver? There are two and only two relevant objects: > the word and the collection. > aCollection selectAnagramsOf: aString > aString anagramsIn: aCollection > would be good names. In a language that did not let you extend system classes, > anagrams(of: aString, in: aCollection) > would be good, but Smalltalk is not such a language. > > 'findAnagramsCandidates:subject:' is intention-revealing, but is not > good English. > Well, maybe the intentions could be revealed a bit better. > What is the subject of an anagram? No idea. > What is an 'anagramsCandidate'? No idea. > What is the difference between an 'anagram' and an 'anagramCandidate'? > > <whatever> anagramsOf: aString in: aCollection > <whatever> selectFrom: aCollection anagramsOf: aString > > > On Mon, 6 Jan 2020 at 03:07, Roelof Wobben via Pharo-users > <pharo-users(a)lists.pharo.org> wrote: > > > > 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 ? > > > > Regards, > > > > Roelof > > > >

Jan. 7, 2020

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

by Richard O'Keefe

I've always considered "all objects respond to #value" as a bug. It certainly is not portable: it wasn't in Smalltalk-80, or Apple Smalltalk, or ANSI Smalltalk, and it isn't in GNU Smalltalk or Dolphin Smalltalk or VisualWorks. It's a peculiarity of Squeak/Pharo and Smalltalk/X. This is a misfeature that can hide bugs until they are ready to hurt you. On Mon, 6 Jan 2020 at 12:13, Santiago Dandois <santids97(a)gmail.com> wrote: > > It's better (conceptually and in performance) to use the inner block, but is not always necessary. The #or: message sends the `value` message to it's collaborator if the bolean is false. Blocks responds to value executing theirs code, but all objects respond to value since it's defined in the Object class as ^self. Therefore, the result is the same but the messages involved and the order in which they are being sent are not. In performance, for the case where the first bolean was true, is better the one with the surrounding block , since the code inside it is never being executed. > > You should really try both versions with the debugger to see it by yourself. > > Cheers, > Santiago Dandois > > El dom., 5 ene. 2020 a las 19:53, xap (<xap(a)router.33mail.com>) escribiÃ³: >> >> thx Rixhard. looks like or: takes an 'alternativeBlock', i.e. a block. >> however substituting a parenthesized expression (or what i assume is one) as >> I did before, in place of the inner block, w/ no other changes has the >> method continue to work as expected, hence my question. *shrug* i need to >> rtfm :-/ >> >> >> >> -- >> Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html >>

Jan. 7, 2020

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

by Richard O'Keefe

What is the receiver? There are two and only two relevant objects: the word and the collection. aCollection selectAnagramsOf: aString aString anagramsIn: aCollection would be good names. In a language that did not let you extend system classes, anagrams(of: aString, in: aCollection) would be good, but Smalltalk is not such a language. 'findAnagramsCandidates:subject:' is intention-revealing, but is not good English. Well, maybe the intentions could be revealed a bit better. What is the subject of an anagram? No idea. What is an 'anagramsCandidate'? No idea. What is the difference between an 'anagram' and an 'anagramCandidate'? <whatever> anagramsOf: aString in: aCollection <whatever> selectFrom: aCollection anagramsOf: aString On Mon, 6 Jan 2020 at 03:07, Roelof Wobben via Pharo-users <pharo-users(a)lists.pharo.org> wrote: > > 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 ? > > Regards, > > Roelof > >

Jan. 7, 2020

Re: [Pharo-users] [ANN] XMLParserHTML moved to GitHub

by LawsonEnglish

Torsten Bergmann wrote > Hi, > > > You can load using > > Metacello new > baseline: 'XMLParserHTML'; > repository: 'github://pharo-contributions/XML-XMLParserHTML/src'; > load. > > > Bye > T. Hi, I'm trying to use the sample code in the pharo screen scraping booklet â http://books.pharo.org/booklet-Scraping/pdf/2018-09-02-scrapingbook.pdf â but while everything appears to load, I'm getting an odd behavior from: /| ingredientsXML | ingredientsXML := XMLHTMLParser parseURL: 'https://ndb.nal.usda.gov/ndb/search/list?sort=ndb&ds=Standard+Reference'. ingredientsXML inspect/ "#new was sent to nil" No matter what URL I use, I get the same message. I'm using Mac OS Catalina so I thought I might have some strange Mac OS security issue (like it was quietly refusing to allow Pharo to access the internet), but I tested with squeak and the old /html :=(HtmlParser parse: 'https://ndb.nal.usda.gov/ndb/search/list?sort=ndb&ds=Standard+Reference' asUrl retrieveContents content)/ and that returns actual html without any problems. Suggestions? Thanks. L -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

Jan. 7, 2020

Re: [Pharo-users] can I make this so the vm would not be not responsibe when running the tests

by Richard O'Keefe

Well, no. This is not a particularly "nice vehicle for programmers to familiarise themselves with recursion". To start with, a quick web search turns up https://en.wikipedia.org/wiki/Wheat_and_chessboard_problem. Problems where the result depend on previous results often fall into the "dynamic programming" category, with Object subclass: #ChessBoard instanceVariableNames: 'board sum' class methods for: 'instance creation' new: n ^self new initialize: n methods for: 'initializing; initialize: n board := Array new: n squared. board at: 1 put: 1. 2 to: board size do: [:i | board at: i put: (board at: i - 1) * 2]. sum := 0. board do: [:each | sum := sum + each]. ^self methods for: 'accessing' squareAt: i ^board at: i total ^sum being the most obvious elementary implementation. The very description of the problem suggests an iterative approach. To find a nice problem for recursion, you have to find one where tabulation is *not* a good strategy. On Mon, 6 Jan 2020 at 08:06, Ben Coman <btc(a)openinworld.com> wrote: > > Hi Richard, > > Just fyi, the aim of Exercism is not to teach programming. Its aim is for experienced programmers to fast-start in new languages. > It just happens to that new programmers also use Exercism and there is some catering in the exercise text for this. > > The grains exercise provides a nice vehicle for programmers to familiarize themselves with recursion in Pharo, > and the hint for the exercise says "These kinds of problems (where an answer is dependent on a previous) one are often called recursion" > which is why Roelof is approaching the problem this way. > > That said, any solution will do. Your advice on alternative considerations is insightful and always good to read. > > cheers -ben > > On Mon, 6 Jan 2020 at 00:25, Richard O'Keefe <raoknz(a)gmail.com> wrote: >> >> I did not ask why you were validating input. >> I asked about why you *repeatedly* validated input. >> >> Think of it this way: >> publicMethod: arg1 also: arg2 >> ... check arg1 ... >> ... check arg2 ... >> ^self privateMethod: arg1 also: arg2 >> >> privateMethod: arg1 also: arg2 >> ... trust that arg1 and arg2 are valide ... >> ... recursive calls use #privateMethod:andAlso: ... >> ... not #publicMethod:andAlso: and must ensure ... >> ... that arguments are valid by construction ... >> >> In my solution to the "Grains" exercism, I have >> atSquare: n -- checks its argument >> total ^(1 bitShift: 64) - 1 >> You are required to implement these two methods, true. >> You are NOT required to implement #total by calling #atSquare:. >> Not even once. Nor is #atSquare: required to be recursive. >> >> On Mon, 6 Jan 2020 at 02:05, Roelof Wobben <r.wobben(a)home.nl> wrote: >> > >> > Hello Ricard. >> > >> > You mean when I calcualate the total of a board. >> > That is because on when I had to calculate the number of a particular >> > field there were tests where the number was lower then zero or higher >> > then 64 which makes no sense. >> > >> > But im open for a solution where on a particular field I could check for >> > that and for the total I do not need that part. >> > >> > Roelof >> > >> > >> > >> > Op 5-1-2020 om 13:58 schreef Richard O'Keefe: >> > > 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 >> > >>> >> > >>> >> > >>

Jan. 7, 2020

Re: [Pharo-users] Prof Stef questions

by xap

yeesh, this just may take more than the few hours i'd initially penciled in the sven-article i read earlier was on medium, i think. as is this calculator one. both read like medium articles ... and suggest an overarching editorial tone, no? unless all medium authors belong to the strunk-and-white-relaxed-for-the-millennium school of writing or some such ;-) there's a quip attributed u.s. justice brandeis: there is no good writing; only good re-writing. applies as much to slate articles, and to code, as it does to supreme court opinions :-/ quips aside i'm always grateful for structured and graduated presentation, and clean/consistent/elegant writing, so many thx sven, and other authors! -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

Jan. 7, 2020

Re: [Pharo-users] Prof Stef questions

by tbrunz

I should have recommended the MOOC as well... I did ProfStef, then PBE5 (in Pharo 6.1), then the MOOC. (I did the MOOC in 6.1 also, downloading and installing the components that come "pre-assembled" in the MOOC image template you can clone in Pharo-Launcher.) Oh, and for your comment about Sven: He's a excellent writer, too! An interesting challenge is to recreate his HP-35 calculator "example" -- mainly because he didn't intend it to be a tutorial, so there's a bit of "fill in the blanks" you'll be challenged with. But it will do a lot to show you how to create native GUI apps and a web app -- of the same thing, allowing you to compare, which is nice. https://medium.com/concerning-pharo/rediscovering-the-ux-of-the-legendary-h… And it's yet another example of how good a writer Sven is, for the technical & not-tech sides of things. -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

Jan. 7, 2020