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Re: [Pharo-users] Uptime

by CÃ©drick BÃ©ler

Clearly amazing ð Is it the setup you use ? https://ci.inria.fr/pharo-contribution/job/EnterprisePharoBook/lastSuccessf… Cheers, Cedrick PS: btw Sven, we (with a group of students did a naive and simple url shortener that would fit nicely to default zinc demos ;-) Here is the script for accessing registered urls (sweet): server := (ZnServer startDefaultOn: 9999) onRequestRespond: [ :request | | key | key := request requestLine uri segments last. dataBase at: key ifPresent: [:val | ZnResponse redirect: val ] ifAbsent: [ZnResponse badRequest: request]. ]. > Le 12 mai 2020 Ã 10:06, Sven Van Caekenberghe <sven(a)stfx.eu> a Ã©crit : > > ï»¿Hi, > > So here is a little anecdote from the real world. I was planning to update the OS on my Linux server, from Ubuntu 18.04 LTS to 20.04 LTS (Long Term Support). This small (Digital Ocean, 1GB RAM, 1 Core) cloud server runs 3 Pharo images with public facing web sites. > > The machine itself reports: > > $ uptime > 12:37:50 up 530 days, 21:46, 1 user, load average: 0.02, 0.04, 0.01 > > which means it hasn't been powered down or didn't restart in 530 days. > > I was surprised to discover that 2 of the Pharo images on that machine did just as well: > > $ ./repl.sh > Connecting to Telnet REPL at locahost:41011 > Trying 127.0.0.1... > Connected to localhost. > Escape character is '^]'. > Neo Console Pharo-7.0+alpha.build.660.sha.2eb9bd2f41e7b0bd8f9f4190906910f83c178ab1 (32 Bit) > pharo> get system.uptime > 405 days 20 hours 29 minutes > pharo> quit > Bye! > > $ ./repl.sh > Connecting to Telnet REPL at locahost:41001 > Trying 127.0.0.1... > Connected to localhost. > Escape character is '^]'. > Neo Console Pharo4.0 of 18 March 2013 update 40620 >> get system.uptime > 530 days 21 hours 44 minutes >> quit > Bye! > > So both Pharo 7 and Pharo 4 kept on doing their jobs for a very long time. I think this is a testament to the stability of Pharo and to what is possible. > > Regards, > > Sven > > -- > Sven Van Caekenberghe > Proudly supporting Pharo > http://pharo.org > http://association.pharo.org > http://consortium.pharo.org > >

May 12, 2020

Uptime

by Sven Van Caekenberghe

Hi, So here is a little anecdote from the real world. I was planning to update the OS on my Linux server, from Ubuntu 18.04 LTS to 20.04 LTS (Long Term Support). This small (Digital Ocean, 1GB RAM, 1 Core) cloud server runs 3 Pharo images with public facing web sites. The machine itself reports: $ uptime 12:37:50 up 530 days, 21:46, 1 user, load average: 0.02, 0.04, 0.01 which means it hasn't been powered down or didn't restart in 530 days. I was surprised to discover that 2 of the Pharo images on that machine did just as well: $ ./repl.sh Connecting to Telnet REPL at locahost:41011 Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. Neo Console Pharo-7.0+alpha.build.660.sha.2eb9bd2f41e7b0bd8f9f4190906910f83c178ab1 (32 Bit) pharo> get system.uptime 405 days 20 hours 29 minutes pharo> quit Bye! $ ./repl.sh Connecting to Telnet REPL at locahost:41001 Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. Neo Console Pharo4.0 of 18 March 2013 update 40620 > get system.uptime 530 days 21 hours 44 minutes > quit Bye! So both Pharo 7 and Pharo 4 kept on doing their jobs for a very long time. I think this is a testament to the stability of Pharo and to what is possible. Regards, Sven -- Sven Van Caekenberghe Proudly supporting Pharo http://pharo.org http://association.pharo.org http://consortium.pharo.org

May 12, 2020

Re: [Pharo-users] mentor question 4

by Richard Sargent

Richard, your diligence is awesome! I'm left feeling that, generally, objects should not implement nor understand #asString. I realize there is a lot of room for debate on this subject. On May 11, 2020 10:12:10 PM PDT, Richard O'Keefe <raoknz(a)gmail.com> wrote: >For what it's worth, here's a moderately thorough examination of >several >different Smalltalk systems. >Let A = astc, D = Dolphin, G = GNU Smalltalk, Q = Squeak, > S = ANSI standard, T = Strongtalk, V = VisualWorks, X = ST/X > >#asString > >ADGPQST!X Character => String with: self >ADGPQSTVX String => self >ADGPQSTVX Symbol => String withAll: self >......... Text/Paragraph, where provided, => underlying string. >A-G-----X Collection => String withAll: self >---PQ---- Collection => self printString >A........ ByteArray => "decoded as Unicode" >.DGPQ-TVX ByteArray => "decoded as Latin1" >ADG.Q..VX Filename => "unparse (Filename, FilePath, whatever) >AdgpQ.TVX URI => "unparse (ZnUrl in P) >Ad.PQ...X UUID => "unparse (d, GUID equivalent)" >.DGpq...X Number => self displayString "or self printString, maybe via >Object" >...PQ...X Object => self printString > >There's a rough consensus here: > - if something *is* textual (Character, String, Symbol, Text, > Paragraph) #asString returns it as a normal string > - if something is a parsed form of structured text (file name, > URI, UUID) its unparsed form is returned, converting it back > should yield an equal parsed form > - if something is a byte array, it may be converted to a string > (the rule is to preserve the bytes, my library presumes byte > arrays are UTF8-encoded) > - if numbers are accepted at all, their #printString is returned > - if is none of the above, but has a #name or #title, that is > commonly the result. > >The open question is what converting an array of characters using >#asString will do. There is at least one Smalltalk out there >where #(65 66 67) asString => 'ABC', but that's a step further >than I personally want, though it is consistent with ByteArray. > > > > >On Tue, 12 May 2020 at 11:16, Jerry Kott <jkott(a)image-ware.com> wrote: > >> Hi all, >> >> Iâve been lurking so far, but I must add my voice here and agree with >> Richard. >> >> The malleability of Smalltalk tempts people into implementing >#asString, >> #name, and similar semantically ambiguous method names. Like Richard, >I >> regretted every single time I (or someone else on my team before me) >> decided to use these. It goes back to âSmalltalk with Styleâ >(probably the >> best little red book you could ever own): write intention revealing >code >> whenever you can, and comment liberally when you canât. >> >> *Jerry Kott* >> This message has been digitally signed. >> PGP Fingerprint: >> A9181736DD2F1B6CC7CF9E51AC8514F48C0979A5 >> >> >> >> On 11-05-2020, at 2:48 PM, Richard Sargent <rsargent(a)5x5.on.ca> >wrote: >> >> >> >> On May 11, 2020 2:19:49 PM PDT, Richard O'Keefe <raoknz(a)gmail.com> >wrote: >> >> I was saying that I expected #($a $b $c) asString ==> 'abc'. >> >> >> Over the years, I found myself being opposed to the idea that all >objects >> can sensibly have an #asString implementation. When it's been done, >it >> ultimately caused more problems than it solved. >> >> Consider $(48 49 50) asString. Do you expect it to give you a string >with >> all the digits? Or perhaps it's meant to interpret the elements as >> byte-like things, as you would need for "String withAll: >aCollection". So, >> the numbers could be interpreted as codepoints, as they are in a >ByteArray. >> >> But, what does "(Array with: Object new with: ProcessScheduler) >asString" >> mean? >> >> It seems to me that having all objects understand #asString leads to >> confusion. >> >> If you want an array to print as its literal representation, >implement >> #printAsLiteral, so that your intention is clear. >> >> >> If you want something that can be read back, that's what #storeString >> is for, >> >> On Tue, 12 May 2020 at 01:28, StÃ©phane Ducasse >> <stephane.ducasse(a)inria.fr> wrote: >> >> >> >> >> On 5 May 2020, at 16:16, Richard O'Keefe <raoknz(a)gmail.com> wrote: >> >> By the way, while playing with this problem, I ran into a moderately >> painful issue. >> >> There is a reason that Smalltalk has both #printString (to get a >> printable representation of an object) and #asString (to convert a >> sequence to another kind of sequence with the same elements.) If I >> *want* #printString, I know where to find it. The definition in my >> Smalltalk no reads >> >> asString >> "What should #($a $b $c) do? >> - Blue Book, Inside Smalltalk, Apple Smalltalk-80: >> there is no #asString. >> - ANSI, VW, Dolphin, CSOM: >> #asString is defined on characters and strings >> (and things like file names and URIs that are sort of >> >> strings), >> >> so expect an error report. >> - VisualAge Smalltalk: >> '($a $b $c)' >> - Squeak and Pharo: >> '#($a $b $c)' >> - GNU Smalltalk, Smalltalk/X, and astc: >> 'abc' >> I don't intend any gratuitous incompatibility, but when there >> is no consensus to be compatible with, one must pick something, >> and this seems most useful. >> " >> ^String withAll: self >> >> Does anyone here know WHY Squeak and Pharo do what they do here? >> >> >> Oops I did not see the quotes on my screen.. >> >> #( a b c) asString >> >> '#(#a #b #c)â >> >> >> this is unclear to me why this is not good but I have no strong >> >> opinion >> >> that this is good. >> >> I worked on printString for literals because I wanted to have >> self evaluating properties for basic literal like in Scheme and >> >> others. >> >> where >> #t >> >> >> #t >> >> And I payed attention that we get the same for literal arrays. >> Now the conversion is open to me. >> >> #($a $b $c) asString >> >> >> '#($a $b $c)â >> >> In fact I do not really understand why a string >> >> #($a $b $c) asString would be '(a b c)â >> and its use >> if this is to nicely display in the ui I would have >> displayString doing it. >> >> S. >> >> >> >> On Wed, 6 May 2020 at 01:20, Richard O'Keefe <raoknz(a)gmail.com> >> >> wrote: >> >> >> >> The irony is that the code I was responding to ISN'T obviously >> >> correct. >> >> Indeed, I found it rather puzzling. >> The problem specification says that the input string may contain >> >> digits >> >> AND SPACES. The original message includes this: >> >> Strings of length 1 or less are not valid. Spaces are allowed in the >> input, but they should be stripped before checking. All other >> non-digit characters are disallowed. >> >> Now it isn't clear what "disallowed" means. I took it to mean "may >> >> occur and >> >> should simply mean the input is rejected as invalid." Perhaps "may >> >> not occur" >> >> was the intention. So we shall not quibble about such characters. >> >> But I can't for the life of me figure out how Trygve's code checks >> >> for spaces. >> >> One reason this is an issue is that the behaviour of #digitValue is >> >> not >> >> consistent between systems. >> Character space digitValue >> does not exist in the ANSI standard >> answers -1 in many Smalltalks (which is a pain) >> answers a positive integer that can't be mistake for a digit in my >> >> Smalltalk >> >> raises an exception in some Smalltalks. >> >> This is a comment I now have in my Smalltalk library for #digitValue >> "This is in the Blue Book, but unspecified on non-digits. >> Squeak, Pharo, Dolphin, VW, VAST, and Apple Smalltalk-80 >> answer -1 for characters that are not digits (or ASCII >> >> letters), >> >> which is unfortunate but consistent with Inside Smalltalk >> which specifies this result for non-digits. >> ST/X and GST raise an exception which is worse. >> Digitalk ST/V documentation doesn't specify the result. >> This selector is *much* easier to use safely if it >> returns a 'large' (>= 36) value for non-digits." >> >> Let's compare three versions, the two I compared last time, >> and the "version A" code I discussed before, which to my mind >> is fairly readable. >> >> "Don't add slowness": 1 (normalised time) >> "Trygve's code": 6.5 >> "High level code": 30.6 (or 4.7 times slower than Trygve's) >> >> Here's the "High level code". >> ^(aString allSatisfy: [:each | each isSpace or: [each isDigit]]) >> >> and: [ >> >> |digitsReverse| >> digitsReverse := (aString select: [:each | each isDigit]) >> >> reverse. >> >> digitsReverse size > 1 and: [ >> |evens odds evenSum oddSum| >> odds := digitsReverse withIndexSelect: [:y :i | i odd]. >> evens := digitsReverse withIndexSelect: [:x :i | i even]. >> oddSum := odds detectSum: [:y | y digitValue]. >> evenSum := evens detectSum: [:x | >> #(0 2 4 6 8 1 3 5 7 9) at: x digitValue + 1]. >> (oddSum + evenSum) \\ 10 = 0]] >> >> This is the kind of code I was recommending that Roelof write. >> >> As a rough guide, by counting traversals (including ones inside >> >> existing >> >> methods), I'd expect the "high level" code to be at least 10 times >> >> slower >> >> than the "no added slowness" code. >> >> We are in vehement agreement that there is a time to write high level >> really obvious easily testable and debuggable code, and that's most >> of the time, especially with programming exercises. >> >> I hope that we are also in agreement that factors of 30 (or even 6) >> *can* be a serious problem. I mean, if I wanted something that slow, >> I'd use Ruby. >> >> I hope we are also agreed that (with the exception of investigations >> like this one) the time to hack on something to make it faster is >> >> AFTER >> >> you have profiled it and determined that you have a problem. >> >> But I respectfully suggest that there is a difference taking slowness >> >> OUT >> >> and simply not going out of your way to add slowness in the first >> >> place. >> >> >> I'd also like to remark that my preference for methods that traverse >> >> a >> >> sequence exactly once has more to do with Smalltalk protocols than >> with efficiency. If the only method I perform on an object is #do: >> the method will work just as well for readable streams as for >> collections. If the only method I perform on an object is >> >> #reverseDo: >> >> the method will work just as well for Read[Write]Streams as for >> SequenceReadableCollections, at least in my library. It's just like >> trying to write #mean so that it works for Durations as well as >> >> Numbers. >> >> >> Oh heck, I suppose I should point out that much of the overheads in >> this case could be eliminated by a Self-style compiler doing dynamic >> inlining + loop fusion. There's no reason *in principle*, given >> >> enough >> >> people, money, and time, that the differences couldn't be greatly >> reduced in Pharo. >> >> On Tue, 5 May 2020 at 21:50, Trygve Reenskaug <trygver(a)ifi.uio.no> >> >> wrote: >> >> >> >> Richard, >> >> Thank you for looking at the code. It is comforting to learn that the >> >> code has been executed for a large number of examples without >breaking. >> The code is not primarily written for execution but for being read >and >> checked by the human end user. It would be nice if we could also >check >> that it gave the right answers, but I don't know how to do that. >> >> >> The first question is: Can a human domain expert read the code and >> >> sign their name for its correctness? >> >> >> >> When this is achieved, a programming expert will transcribe the first >> >> code to a professional quality program. This time, the second code >> should be reviewed by an independent programmer who signs their name >> for its correct transcription from the first version. >> >> >> --Trygve >> >> PS: In his 1991 Turing Award Lecture, Tony Hoare said: "There are two >> >> ways of constructing a software design: One way is to make it so >simple >> that there are obviously no deficiencies and the other is to make it >so >> complicated that there are no obvious deficiencies. The first method >is >> far more difficult." >> >> >> --Trygve >> >> On tirsdag.05.05.2020 04:41, Richard O'Keefe wrote: >> >> As a coding experiment, I adapted Trygve Reenskoug's code to my >> Smalltalk compiler, put in my code slightly tweaked, and benchmarked >> them on randomly generated data. >> >> Result: a factor of 6.3. >> >> In Squeak it was a factor of ten. >> >> I had not, in all honesty, expected it to to be so high. >> >> On Tue, 5 May 2020 at 02:00, Trygve Reenskaug <trygver(a)ifi.uio.no> >> >> wrote: >> >> >> A coding experiment. >> Consider a Scrum development environment. Every programming team has >> >> an end user as a member. >> >> The team's task is to code a credit card validity check. >> A first goal is that the user representative shall read the code and >> >> agree that it is a correct rendering of their code checker: >> >> >> luhnTest: trialNumber >> | s1 odd s2 even charValue reverse | >> ----------------------------------------------- >> " Luhn test according to Rosetta" >> "Reverse the order of the digits in the number." >> reverse := trialNumber reversed. >> "Take the first, third, ... and every other odd digit in the reversed >> >> digits and sum them to form the partial sum s1" >> >> s1 := 0. >> odd := true. >> reverse do: >> [:char | >> odd >> ifTrue: [ >> s1 := s1 + char digitValue. >> ]. >> odd := odd not >> ]. >> "Taking the second, fourth ... and every other even digit in the >> >> reversed digits: >> >> Multiply each digit by two and sum the digits if the answer is >> >> greater than nine to form partial sums for the even digits" >> >> "The subtracting 9 gives the same answer. " >> "Sum the partial sums of the even digits to form s2" >> s2 := 0. >> even := false. >> reverse do: >> [:char | >> even >> ifTrue: [ >> charValue := char digitValue * 2. >> charValue > 9 ifTrue: [charValue := charValue - >> >> 9]. >> >> s2 := s2 + charValue >> ]. >> even := even not >> ]. >> "If s1 + s2 ends in zero then the original number is in the form of a >> >> valid credit card number as verified by the Luhn test." >> >> ^(s1 + s2) asString last = $0 >> --------------------------------- >> Once this step is completed, the next step will be to make the code >> >> right without altering the algorithm (refactoring). The result should >> be readable and follow the team's conventions. >> >> >> >> P.S. code attached. >> >> >> -- >> >> The essence of object orientation is that objects collaborate to >> >> achieve a goal. >> >> Trygve Reenskaug mailto: trygver(a)ifi.uio.no >> Morgedalsvn. 5A http://folk.uio.no/trygver/ >> N-0378 Oslo http://fullOO.info >> Norway Tel: (+47) 468 58 625 >> >> >> >> -------------------------------------------- >> StÃ©phane Ducasse >> http://stephane.ducasse.free.fr / http://www.pharo.org >> 03 59 35 87 52 >> Assistant: Julie Jonas >> FAX 03 59 57 78 50 >> TEL 03 59 35 86 16 >> S. Ducasse - Inria >> 40, avenue Halley, >> Parc Scientifique de la Haute Borne, BÃ¢t.A, Park Plaza >> Villeneuve d'Ascq 59650 >> France >> >> >> >> >>

May 12, 2020

Re: [Pharo-users] mentor question 4

by Richard O'Keefe

For what it's worth, here's a moderately thorough examination of several different Smalltalk systems. Let A = astc, D = Dolphin, G = GNU Smalltalk, Q = Squeak, S = ANSI standard, T = Strongtalk, V = VisualWorks, X = ST/X #asString ADGPQST!X Character => String with: self ADGPQSTVX String => self ADGPQSTVX Symbol => String withAll: self ......... Text/Paragraph, where provided, => underlying string. A-G-----X Collection => String withAll: self ---PQ---- Collection => self printString A........ ByteArray => "decoded as Unicode" .DGPQ-TVX ByteArray => "decoded as Latin1" ADG.Q..VX Filename => "unparse (Filename, FilePath, whatever) AdgpQ.TVX URI => "unparse (ZnUrl in P) Ad.PQ...X UUID => "unparse (d, GUID equivalent)" .DGpq...X Number => self displayString "or self printString, maybe via Object" ...PQ...X Object => self printString There's a rough consensus here: - if something *is* textual (Character, String, Symbol, Text, Paragraph) #asString returns it as a normal string - if something is a parsed form of structured text (file name, URI, UUID) its unparsed form is returned, converting it back should yield an equal parsed form - if something is a byte array, it may be converted to a string (the rule is to preserve the bytes, my library presumes byte arrays are UTF8-encoded) - if numbers are accepted at all, their #printString is returned - if is none of the above, but has a #name or #title, that is commonly the result. The open question is what converting an array of characters using #asString will do. There is at least one Smalltalk out there where #(65 66 67) asString => 'ABC', but that's a step further than I personally want, though it is consistent with ByteArray. On Tue, 12 May 2020 at 11:16, Jerry Kott <jkott(a)image-ware.com> wrote: > Hi all, > > Iâve been lurking so far, but I must add my voice here and agree with > Richard. > > The malleability of Smalltalk tempts people into implementing #asString, > #name, and similar semantically ambiguous method names. Like Richard, I > regretted every single time I (or someone else on my team before me) > decided to use these. It goes back to âSmalltalk with Styleâ (probably the > best little red book you could ever own): write intention revealing code > whenever you can, and comment liberally when you canât. > > *Jerry Kott* > This message has been digitally signed. > PGP Fingerprint: > A9181736DD2F1B6CC7CF9E51AC8514F48C0979A5 > > > > On 11-05-2020, at 2:48 PM, Richard Sargent <rsargent(a)5x5.on.ca> wrote: > > > > On May 11, 2020 2:19:49 PM PDT, Richard O'Keefe <raoknz(a)gmail.com> wrote: > > I was saying that I expected #($a $b $c) asString ==> 'abc'. > > > Over the years, I found myself being opposed to the idea that all objects > can sensibly have an #asString implementation. When it's been done, it > ultimately caused more problems than it solved. > > Consider $(48 49 50) asString. Do you expect it to give you a string with > all the digits? Or perhaps it's meant to interpret the elements as > byte-like things, as you would need for "String withAll: aCollection". So, > the numbers could be interpreted as codepoints, as they are in a ByteArray. > > But, what does "(Array with: Object new with: ProcessScheduler) asString" > mean? > > It seems to me that having all objects understand #asString leads to > confusion. > > If you want an array to print as its literal representation, implement > #printAsLiteral, so that your intention is clear. > > > If you want something that can be read back, that's what #storeString > is for, > > On Tue, 12 May 2020 at 01:28, StÃ©phane Ducasse > <stephane.ducasse(a)inria.fr> wrote: > > > > > On 5 May 2020, at 16:16, Richard O'Keefe <raoknz(a)gmail.com> wrote: > > By the way, while playing with this problem, I ran into a moderately > painful issue. > > There is a reason that Smalltalk has both #printString (to get a > printable representation of an object) and #asString (to convert a > sequence to another kind of sequence with the same elements.) If I > *want* #printString, I know where to find it. The definition in my > Smalltalk no reads > > asString > "What should #($a $b $c) do? > - Blue Book, Inside Smalltalk, Apple Smalltalk-80: > there is no #asString. > - ANSI, VW, Dolphin, CSOM: > #asString is defined on characters and strings > (and things like file names and URIs that are sort of > > strings), > > so expect an error report. > - VisualAge Smalltalk: > '($a $b $c)' > - Squeak and Pharo: > '#($a $b $c)' > - GNU Smalltalk, Smalltalk/X, and astc: > 'abc' > I don't intend any gratuitous incompatibility, but when there > is no consensus to be compatible with, one must pick something, > and this seems most useful. > " > ^String withAll: self > > Does anyone here know WHY Squeak and Pharo do what they do here? > > > Oops I did not see the quotes on my screen.. > > #( a b c) asString > > '#(#a #b #c)â > > > this is unclear to me why this is not good but I have no strong > > opinion > > that this is good. > > I worked on printString for literals because I wanted to have > self evaluating properties for basic literal like in Scheme and > > others. > > where > #t > > > #t > > And I payed attention that we get the same for literal arrays. > Now the conversion is open to me. > > #($a $b $c) asString > > > '#($a $b $c)â > > In fact I do not really understand why a string > > #($a $b $c) asString would be '(a b c)â > and its use > if this is to nicely display in the ui I would have > displayString doing it. > > S. > > > > On Wed, 6 May 2020 at 01:20, Richard O'Keefe <raoknz(a)gmail.com> > > wrote: > > > > The irony is that the code I was responding to ISN'T obviously > > correct. > > Indeed, I found it rather puzzling. > The problem specification says that the input string may contain > > digits > > AND SPACES. The original message includes this: > > Strings of length 1 or less are not valid. Spaces are allowed in the > input, but they should be stripped before checking. All other > non-digit characters are disallowed. > > Now it isn't clear what "disallowed" means. I took it to mean "may > > occur and > > should simply mean the input is rejected as invalid." Perhaps "may > > not occur" > > was the intention. So we shall not quibble about such characters. > > But I can't for the life of me figure out how Trygve's code checks > > for spaces. > > One reason this is an issue is that the behaviour of #digitValue is > > not > > consistent between systems. > Character space digitValue > does not exist in the ANSI standard > answers -1 in many Smalltalks (which is a pain) > answers a positive integer that can't be mistake for a digit in my > > Smalltalk > > raises an exception in some Smalltalks. > > This is a comment I now have in my Smalltalk library for #digitValue > "This is in the Blue Book, but unspecified on non-digits. > Squeak, Pharo, Dolphin, VW, VAST, and Apple Smalltalk-80 > answer -1 for characters that are not digits (or ASCII > > letters), > > which is unfortunate but consistent with Inside Smalltalk > which specifies this result for non-digits. > ST/X and GST raise an exception which is worse. > Digitalk ST/V documentation doesn't specify the result. > This selector is *much* easier to use safely if it > returns a 'large' (>= 36) value for non-digits." > > Let's compare three versions, the two I compared last time, > and the "version A" code I discussed before, which to my mind > is fairly readable. > > "Don't add slowness": 1 (normalised time) > "Trygve's code": 6.5 > "High level code": 30.6 (or 4.7 times slower than Trygve's) > > Here's the "High level code". > ^(aString allSatisfy: [:each | each isSpace or: [each isDigit]]) > > and: [ > > |digitsReverse| > digitsReverse := (aString select: [:each | each isDigit]) > > reverse. > > digitsReverse size > 1 and: [ > |evens odds evenSum oddSum| > odds := digitsReverse withIndexSelect: [:y :i | i odd]. > evens := digitsReverse withIndexSelect: [:x :i | i even]. > oddSum := odds detectSum: [:y | y digitValue]. > evenSum := evens detectSum: [:x | > #(0 2 4 6 8 1 3 5 7 9) at: x digitValue + 1]. > (oddSum + evenSum) \\ 10 = 0]] > > This is the kind of code I was recommending that Roelof write. > > As a rough guide, by counting traversals (including ones inside > > existing > > methods), I'd expect the "high level" code to be at least 10 times > > slower > > than the "no added slowness" code. > > We are in vehement agreement that there is a time to write high level > really obvious easily testable and debuggable code, and that's most > of the time, especially with programming exercises. > > I hope that we are also in agreement that factors of 30 (or even 6) > *can* be a serious problem. I mean, if I wanted something that slow, > I'd use Ruby. > > I hope we are also agreed that (with the exception of investigations > like this one) the time to hack on something to make it faster is > > AFTER > > you have profiled it and determined that you have a problem. > > But I respectfully suggest that there is a difference taking slowness > > OUT > > and simply not going out of your way to add slowness in the first > > place. > > > I'd also like to remark that my preference for methods that traverse > > a > > sequence exactly once has more to do with Smalltalk protocols than > with efficiency. If the only method I perform on an object is #do: > the method will work just as well for readable streams as for > collections. If the only method I perform on an object is > > #reverseDo: > > the method will work just as well for Read[Write]Streams as for > SequenceReadableCollections, at least in my library. It's just like > trying to write #mean so that it works for Durations as well as > > Numbers. > > > Oh heck, I suppose I should point out that much of the overheads in > this case could be eliminated by a Self-style compiler doing dynamic > inlining + loop fusion. There's no reason *in principle*, given > > enough > > people, money, and time, that the differences couldn't be greatly > reduced in Pharo. > > On Tue, 5 May 2020 at 21:50, Trygve Reenskaug <trygver(a)ifi.uio.no> > > wrote: > > > > Richard, > > Thank you for looking at the code. It is comforting to learn that the > > code has been executed for a large number of examples without breaking. > The code is not primarily written for execution but for being read and > checked by the human end user. It would be nice if we could also check > that it gave the right answers, but I don't know how to do that. > > > The first question is: Can a human domain expert read the code and > > sign their name for its correctness? > > > > When this is achieved, a programming expert will transcribe the first > > code to a professional quality program. This time, the second code > should be reviewed by an independent programmer who signs their name > for its correct transcription from the first version. > > > --Trygve > > PS: In his 1991 Turing Award Lecture, Tony Hoare said: "There are two > > ways of constructing a software design: One way is to make it so simple > that there are obviously no deficiencies and the other is to make it so > complicated that there are no obvious deficiencies. The first method is > far more difficult." > > > --Trygve > > On tirsdag.05.05.2020 04:41, Richard O'Keefe wrote: > > As a coding experiment, I adapted Trygve Reenskoug's code to my > Smalltalk compiler, put in my code slightly tweaked, and benchmarked > them on randomly generated data. > > Result: a factor of 6.3. > > In Squeak it was a factor of ten. > > I had not, in all honesty, expected it to to be so high. > > On Tue, 5 May 2020 at 02:00, Trygve Reenskaug <trygver(a)ifi.uio.no> > > wrote: > > > A coding experiment. > Consider a Scrum development environment. Every programming team has > > an end user as a member. > > The team's task is to code a credit card validity check. > A first goal is that the user representative shall read the code and > > agree that it is a correct rendering of their code checker: > > > luhnTest: trialNumber > | s1 odd s2 even charValue reverse | > ----------------------------------------------- > " Luhn test according to Rosetta" > "Reverse the order of the digits in the number." > reverse := trialNumber reversed. > "Take the first, third, ... and every other odd digit in the reversed > > digits and sum them to form the partial sum s1" > > s1 := 0. > odd := true. > reverse do: > [:char | > odd > ifTrue: [ > s1 := s1 + char digitValue. > ]. > odd := odd not > ]. > "Taking the second, fourth ... and every other even digit in the > > reversed digits: > > Multiply each digit by two and sum the digits if the answer is > > greater than nine to form partial sums for the even digits" > > "The subtracting 9 gives the same answer. " > "Sum the partial sums of the even digits to form s2" > s2 := 0. > even := false. > reverse do: > [:char | > even > ifTrue: [ > charValue := char digitValue * 2. > charValue > 9 ifTrue: [charValue := charValue - > > 9]. > > s2 := s2 + charValue > ]. > even := even not > ]. > "If s1 + s2 ends in zero then the original number is in the form of a > > valid credit card number as verified by the Luhn test." > > ^(s1 + s2) asString last = $0 > --------------------------------- > Once this step is completed, the next step will be to make the code > > right without altering the algorithm (refactoring). The result should > be readable and follow the team's conventions. > > > > P.S. code attached. > > > -- > > The essence of object orientation is that objects collaborate to > > achieve a goal. > > Trygve Reenskaug mailto: trygver(a)ifi.uio.no > Morgedalsvn. 5A http://folk.uio.no/trygver/ > N-0378 Oslo http://fullOO.info > Norway Tel: (+47) 468 58 625 > > > > -------------------------------------------- > StÃ©phane Ducasse > http://stephane.ducasse.free.fr / http://www.pharo.org > 03 59 35 87 52 > Assistant: Julie Jonas > FAX 03 59 57 78 50 > TEL 03 59 35 86 16 > S. Ducasse - Inria > 40, avenue Halley, > Parc Scientifique de la Haute Borne, BÃ¢t.A, Park Plaza > Villeneuve d'Ascq 59650 > France > > > > >

May 12, 2020

Re: [Pharo-users] Need help putting my Pharo package under source control

by tbrunz

Also, regarding keeping your images under control, if you haven't downloaded and started using Pharo Launcher, you should! It's a fabulous tool... http://pharo.org/download -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

May 12, 2020

Re: [Pharo-users] Need help putting my Pharo package under source control

by tbrunz

Hi, Your document is definitely out of date! The current version of PBE for version 5, 6, and 7 can be found here: https://github.com/SquareBracketAssociates/UpdatedPharoByExample/releases If you're using Pharo 8 or 9, you'll want the updated version, PBE8, which can be found here: https://github.com/SquareBracketAssociates/PharoByExample80/releases Yes, you can FileOut and FileIn. If you right-click on an item in the System Browser (which was 'Nautilus' until version 7, when it was replaced with 'Calypso'), the last fly-out menu has 'FileOut' listed. (I think you need to send a message in the Playground to use 'FileIn'; I'm not sure, as, like most, I don't use it.) Note that you can no longer (or "shouldn't") use SmalltalkHub; it's deprecated, and if it's not already locked for modifications, it will be shortly. (Then it becomes read-only until late in the year, when the site will be shut down.) So you *should* use GitHub. Since version 7, it's the default repository for Pharo code. There is now a native Git client in Pharo called "Iceberg". It works with GitHub, GitLab, BitBucket, local git repos, and remote git repos. You can create git repos, commit/push/pull, submit PRs, etc. from Iceberg while remaining in the Pharo IDE. You can read more about Iceberg and managing code here: https://github.com/SquareBracketAssociates/Booklet-ManagingCode/releases Have fun! -Ted -- Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

May 12, 2020

Re: [Pharo-users] mentor question 4

by Jerry Kott

Hi all, Iâve been lurking so far, but I must add my voice here and agree with Richard. The malleability of Smalltalk tempts people into implementing #asString, #name, and similar semantically ambiguous method names. Like Richard, I regretted every single time I (or someone else on my team before me) decided to use these. It goes back to âSmalltalk with Styleâ (probably the best little red book you could ever own): write intention revealing code whenever you can, and comment liberally when you canât. Jerry Kott This message has been digitally signed. PGP Fingerprint: A9181736DD2F1B6CC7CF9E51AC8514F48C0979A5 > On 11-05-2020, at 2:48 PM, Richard Sargent <rsargent(a)5x5.on.ca> wrote: > > > > On May 11, 2020 2:19:49 PM PDT, Richard O'Keefe <raoknz(a)gmail.com> wrote: >> I was saying that I expected #($a $b $c) asString ==> 'abc'. > > Over the years, I found myself being opposed to the idea that all objects can sensibly have an #asString implementation. When it's been done, it ultimately caused more problems than it solved. > > Consider $(48 49 50) asString. Do you expect it to give you a string with all the digits? Or perhaps it's meant to interpret the elements as byte-like things, as you would need for "String withAll: aCollection". So, the numbers could be interpreted as codepoints, as they are in a ByteArray. > > But, what does "(Array with: Object new with: ProcessScheduler) asString" mean? > > It seems to me that having all objects understand #asString leads to confusion. > > If you want an array to print as its literal representation, implement #printAsLiteral, so that your intention is clear. > > >> If you want something that can be read back, that's what #storeString >> is for, >> >> On Tue, 12 May 2020 at 01:28, StÃ©phane Ducasse >> <stephane.ducasse(a)inria.fr> wrote: >>> >>> >>> >>> On 5 May 2020, at 16:16, Richard O'Keefe <raoknz(a)gmail.com> wrote: >>> >>> By the way, while playing with this problem, I ran into a moderately >>> painful issue. >>> >>> There is a reason that Smalltalk has both #printString (to get a >>> printable representation of an object) and #asString (to convert a >>> sequence to another kind of sequence with the same elements.) If I >>> *want* #printString, I know where to find it. The definition in my >>> Smalltalk no reads >>> >>> asString >>> "What should #($a $b $c) do? >>> - Blue Book, Inside Smalltalk, Apple Smalltalk-80: >>> there is no #asString. >>> - ANSI, VW, Dolphin, CSOM: >>> #asString is defined on characters and strings >>> (and things like file names and URIs that are sort of >> strings), >>> so expect an error report. >>> - VisualAge Smalltalk: >>> '($a $b $c)' >>> - Squeak and Pharo: >>> '#($a $b $c)' >>> - GNU Smalltalk, Smalltalk/X, and astc: >>> 'abc' >>> I don't intend any gratuitous incompatibility, but when there >>> is no consensus to be compatible with, one must pick something, >>> and this seems most useful. >>> " >>> ^String withAll: self >>> >>> Does anyone here know WHY Squeak and Pharo do what they do here? >>> >>> >>> Oops I did not see the quotes on my screen.. >>> >>> #( a b c) asString >>>>>> '#(#a #b #c)â >>> >>> this is unclear to me why this is not good but I have no strong >> opinion >>> that this is good. >>> >>> I worked on printString for literals because I wanted to have >>> self evaluating properties for basic literal like in Scheme and >> others. >>> where >>> #t >>>>>> >>> #t >>> >>> And I payed attention that we get the same for literal arrays. >>> Now the conversion is open to me. >>> >>> #($a $b $c) asString >>>>>> >>> '#($a $b $c)â >>> >>> In fact I do not really understand why a string >>> >>> #($a $b $c) asString would be '(a b c)â >>> and its use >>> if this is to nicely display in the ui I would have >>> displayString doing it. >>> >>> S. >>> >>> >>> >>> On Wed, 6 May 2020 at 01:20, Richard O'Keefe <raoknz(a)gmail.com> >> wrote: >>> >>> >>> The irony is that the code I was responding to ISN'T obviously >> correct. >>> Indeed, I found it rather puzzling. >>> The problem specification says that the input string may contain >> digits >>> AND SPACES. The original message includes this: >>> >>> Strings of length 1 or less are not valid. Spaces are allowed in the >>> input, but they should be stripped before checking. All other >>> non-digit characters are disallowed. >>> >>> Now it isn't clear what "disallowed" means. I took it to mean "may >> occur and >>> should simply mean the input is rejected as invalid." Perhaps "may >> not occur" >>> was the intention. So we shall not quibble about such characters. >>> >>> But I can't for the life of me figure out how Trygve's code checks >> for spaces. >>> One reason this is an issue is that the behaviour of #digitValue is >> not >>> consistent between systems. >>> Character space digitValue >>> does not exist in the ANSI standard >>> answers -1 in many Smalltalks (which is a pain) >>> answers a positive integer that can't be mistake for a digit in my >> Smalltalk >>> raises an exception in some Smalltalks. >>> >>> This is a comment I now have in my Smalltalk library for #digitValue >>> "This is in the Blue Book, but unspecified on non-digits. >>> Squeak, Pharo, Dolphin, VW, VAST, and Apple Smalltalk-80 >>> answer -1 for characters that are not digits (or ASCII >> letters), >>> which is unfortunate but consistent with Inside Smalltalk >>> which specifies this result for non-digits. >>> ST/X and GST raise an exception which is worse. >>> Digitalk ST/V documentation doesn't specify the result. >>> This selector is *much* easier to use safely if it >>> returns a 'large' (>= 36) value for non-digits." >>> >>> Let's compare three versions, the two I compared last time, >>> and the "version A" code I discussed before, which to my mind >>> is fairly readable. >>> >>> "Don't add slowness": 1 (normalised time) >>> "Trygve's code": 6.5 >>> "High level code": 30.6 (or 4.7 times slower than Trygve's) >>> >>> Here's the "High level code". >>> ^(aString allSatisfy: [:each | each isSpace or: [each isDigit]]) >> and: [ >>> |digitsReverse| >>> digitsReverse := (aString select: [:each | each isDigit]) >> reverse. >>> digitsReverse size > 1 and: [ >>> |evens odds evenSum oddSum| >>> odds := digitsReverse withIndexSelect: [:y :i | i odd]. >>> evens := digitsReverse withIndexSelect: [:x :i | i even]. >>> oddSum := odds detectSum: [:y | y digitValue]. >>> evenSum := evens detectSum: [:x | >>> #(0 2 4 6 8 1 3 5 7 9) at: x digitValue + 1]. >>> (oddSum + evenSum) \\ 10 = 0]] >>> >>> This is the kind of code I was recommending that Roelof write. >>> >>> As a rough guide, by counting traversals (including ones inside >> existing >>> methods), I'd expect the "high level" code to be at least 10 times >> slower >>> than the "no added slowness" code. >>> >>> We are in vehement agreement that there is a time to write high level >>> really obvious easily testable and debuggable code, and that's most >>> of the time, especially with programming exercises. >>> >>> I hope that we are also in agreement that factors of 30 (or even 6) >>> *can* be a serious problem. I mean, if I wanted something that slow, >>> I'd use Ruby. >>> >>> I hope we are also agreed that (with the exception of investigations >>> like this one) the time to hack on something to make it faster is >> AFTER >>> you have profiled it and determined that you have a problem. >>> >>> But I respectfully suggest that there is a difference taking slowness >> OUT >>> and simply not going out of your way to add slowness in the first >> place. >>> >>> I'd also like to remark that my preference for methods that traverse >> a >>> sequence exactly once has more to do with Smalltalk protocols than >>> with efficiency. If the only method I perform on an object is #do: >>> the method will work just as well for readable streams as for >>> collections. If the only method I perform on an object is >> #reverseDo: >>> the method will work just as well for Read[Write]Streams as for >>> SequenceReadableCollections, at least in my library. It's just like >>> trying to write #mean so that it works for Durations as well as >> Numbers. >>> >>> Oh heck, I suppose I should point out that much of the overheads in >>> this case could be eliminated by a Self-style compiler doing dynamic >>> inlining + loop fusion. There's no reason *in principle*, given >> enough >>> people, money, and time, that the differences couldn't be greatly >>> reduced in Pharo. >>> >>> On Tue, 5 May 2020 at 21:50, Trygve Reenskaug <trygver(a)ifi.uio.no> >> wrote: >>> >>> >>> Richard, >>> >>> Thank you for looking at the code. It is comforting to learn that the >> code has been executed for a large number of examples without breaking. >> The code is not primarily written for execution but for being read and >> checked by the human end user. It would be nice if we could also check >> that it gave the right answers, but I don't know how to do that. >>> >>> The first question is: Can a human domain expert read the code and >> sign their name for its correctness? >>> >>> >>> When this is achieved, a programming expert will transcribe the first >> code to a professional quality program. This time, the second code >> should be reviewed by an independent programmer who signs their name >> for its correct transcription from the first version. >>> >>> --Trygve >>> >>> PS: In his 1991 Turing Award Lecture, Tony Hoare said: "There are two >> ways of constructing a software design: One way is to make it so simple >> that there are obviously no deficiencies and the other is to make it so >> complicated that there are no obvious deficiencies. The first method is >> far more difficult." >>> >>> --Trygve >>> >>> On tirsdag.05.05.2020 04:41, Richard O'Keefe wrote: >>> >>> As a coding experiment, I adapted Trygve Reenskoug's code to my >>> Smalltalk compiler, put in my code slightly tweaked, and benchmarked >>> them on randomly generated data. >>> >>> Result: a factor of 6.3. >>> >>> In Squeak it was a factor of ten. >>> >>> I had not, in all honesty, expected it to to be so high. >>> >>> On Tue, 5 May 2020 at 02:00, Trygve Reenskaug <trygver(a)ifi.uio.no> >> wrote: >>> >>> A coding experiment. >>> Consider a Scrum development environment. Every programming team has >> an end user as a member. >>> The team's task is to code a credit card validity check. >>> A first goal is that the user representative shall read the code and >> agree that it is a correct rendering of their code checker: >>> >>> luhnTest: trialNumber >>> | s1 odd s2 even charValue reverse | >>> ----------------------------------------------- >>> " Luhn test according to Rosetta" >>> "Reverse the order of the digits in the number." >>> reverse := trialNumber reversed. >>> "Take the first, third, ... and every other odd digit in the reversed >> digits and sum them to form the partial sum s1" >>> s1 := 0. >>> odd := true. >>> reverse do: >>> [:char | >>> odd >>> ifTrue: [ >>> s1 := s1 + char digitValue. >>> ]. >>> odd := odd not >>> ]. >>> "Taking the second, fourth ... and every other even digit in the >> reversed digits: >>> Multiply each digit by two and sum the digits if the answer is >> greater than nine to form partial sums for the even digits" >>> "The subtracting 9 gives the same answer. " >>> "Sum the partial sums of the even digits to form s2" >>> s2 := 0. >>> even := false. >>> reverse do: >>> [:char | >>> even >>> ifTrue: [ >>> charValue := char digitValue * 2. >>> charValue > 9 ifTrue: [charValue := charValue - >> 9]. >>> s2 := s2 + charValue >>> ]. >>> even := even not >>> ]. >>> "If s1 + s2 ends in zero then the original number is in the form of a >> valid credit card number as verified by the Luhn test." >>> ^(s1 + s2) asString last = $0 >>> --------------------------------- >>> Once this step is completed, the next step will be to make the code >> right without altering the algorithm (refactoring). The result should >> be readable and follow the team's conventions. >>> >>> >>> P.S. code attached. >>> >>> >>> -- >>> >>> The essence of object orientation is that objects collaborate to >> achieve a goal. >>> Trygve Reenskaug mailto: trygver(a)ifi.uio.no >>> Morgedalsvn. 5A http://folk.uio.no/trygver/ >>> N-0378 Oslo http://fullOO.info >>> Norway Tel: (+47) 468 58 625 >>> >>> >>> >>> -------------------------------------------- >>> StÃ©phane Ducasse >>> http://stephane.ducasse.free.fr / http://www.pharo.org >>> 03 59 35 87 52 >>> Assistant: Julie Jonas >>> FAX 03 59 57 78 50 >>> TEL 03 59 35 86 16 >>> S. Ducasse - Inria >>> 40, avenue Halley, >>> Parc Scientifique de la Haute Borne, BÃ¢t.A, Park Plaza >>> Villeneuve d'Ascq 59650 >>> France >>> > >

May 11, 2020

Re: [Pharo-users] mentor question 4

by Richard Sargent

On May 11, 2020 2:19:49 PM PDT, Richard O'Keefe <raoknz(a)gmail.com> wrote: >I was saying that I expected #($a $b $c) asString ==> 'abc'. Over the years, I found myself being opposed to the idea that all objects can sensibly have an #asString implementation. When it's been done, it ultimately caused more problems than it solved. Consider $(48 49 50) asString. Do you expect it to give you a string with all the digits? Or perhaps it's meant to interpret the elements as byte-like things, as you would need for "String withAll: aCollection". So, the numbers could be interpreted as codepoints, as they are in a ByteArray. But, what does "(Array with: Object new with: ProcessScheduler) asString" mean? It seems to me that having all objects understand #asString leads to confusion. If you want an array to print as its literal representation, implement #printAsLiteral, so that your intention is clear. >If you want something that can be read back, that's what #storeString >is for, > >On Tue, 12 May 2020 at 01:28, StÃ©phane Ducasse ><stephane.ducasse(a)inria.fr> wrote: >> >> >> >> On 5 May 2020, at 16:16, Richard O'Keefe <raoknz(a)gmail.com> wrote: >> >> By the way, while playing with this problem, I ran into a moderately >> painful issue. >> >> There is a reason that Smalltalk has both #printString (to get a >> printable representation of an object) and #asString (to convert a >> sequence to another kind of sequence with the same elements.) If I >> *want* #printString, I know where to find it. The definition in my >> Smalltalk no reads >> >> asString >> "What should #($a $b $c) do? >> - Blue Book, Inside Smalltalk, Apple Smalltalk-80: >> there is no #asString. >> - ANSI, VW, Dolphin, CSOM: >> #asString is defined on characters and strings >> (and things like file names and URIs that are sort of >strings), >> so expect an error report. >> - VisualAge Smalltalk: >> '($a $b $c)' >> - Squeak and Pharo: >> '#($a $b $c)' >> - GNU Smalltalk, Smalltalk/X, and astc: >> 'abc' >> I don't intend any gratuitous incompatibility, but when there >> is no consensus to be compatible with, one must pick something, >> and this seems most useful. >> " >> ^String withAll: self >> >> Does anyone here know WHY Squeak and Pharo do what they do here? >> >> >> Oops I did not see the quotes on my screen.. >> >> #( a b c) asString >> >>> '#(#a #b #c)â >> >> this is unclear to me why this is not good but I have no strong >opinion >> that this is good. >> >> I worked on printString for literals because I wanted to have >> self evaluating properties for basic literal like in Scheme and >others. >> where >> #t >> >>> >> #t >> >> And I payed attention that we get the same for literal arrays. >> Now the conversion is open to me. >> >> #($a $b $c) asString >> >>> >> '#($a $b $c)â >> >> In fact I do not really understand why a string >> >> #($a $b $c) asString would be '(a b c)â >> and its use >> if this is to nicely display in the ui I would have >> displayString doing it. >> >> S. >> >> >> >> On Wed, 6 May 2020 at 01:20, Richard O'Keefe <raoknz(a)gmail.com> >wrote: >> >> >> The irony is that the code I was responding to ISN'T obviously >correct. >> Indeed, I found it rather puzzling. >> The problem specification says that the input string may contain >digits >> AND SPACES. The original message includes this: >> >> Strings of length 1 or less are not valid. Spaces are allowed in the >> input, but they should be stripped before checking. All other >> non-digit characters are disallowed. >> >> Now it isn't clear what "disallowed" means. I took it to mean "may >occur and >> should simply mean the input is rejected as invalid." Perhaps "may >not occur" >> was the intention. So we shall not quibble about such characters. >> >> But I can't for the life of me figure out how Trygve's code checks >for spaces. >> One reason this is an issue is that the behaviour of #digitValue is >not >> consistent between systems. >> Character space digitValue >> does not exist in the ANSI standard >> answers -1 in many Smalltalks (which is a pain) >> answers a positive integer that can't be mistake for a digit in my >Smalltalk >> raises an exception in some Smalltalks. >> >> This is a comment I now have in my Smalltalk library for #digitValue >> "This is in the Blue Book, but unspecified on non-digits. >> Squeak, Pharo, Dolphin, VW, VAST, and Apple Smalltalk-80 >> answer -1 for characters that are not digits (or ASCII >letters), >> which is unfortunate but consistent with Inside Smalltalk >> which specifies this result for non-digits. >> ST/X and GST raise an exception which is worse. >> Digitalk ST/V documentation doesn't specify the result. >> This selector is *much* easier to use safely if it >> returns a 'large' (>= 36) value for non-digits." >> >> Let's compare three versions, the two I compared last time, >> and the "version A" code I discussed before, which to my mind >> is fairly readable. >> >> "Don't add slowness": 1 (normalised time) >> "Trygve's code": 6.5 >> "High level code": 30.6 (or 4.7 times slower than Trygve's) >> >> Here's the "High level code". >> ^(aString allSatisfy: [:each | each isSpace or: [each isDigit]]) >and: [ >> |digitsReverse| >> digitsReverse := (aString select: [:each | each isDigit]) >reverse. >> digitsReverse size > 1 and: [ >> |evens odds evenSum oddSum| >> odds := digitsReverse withIndexSelect: [:y :i | i odd]. >> evens := digitsReverse withIndexSelect: [:x :i | i even]. >> oddSum := odds detectSum: [:y | y digitValue]. >> evenSum := evens detectSum: [:x | >> #(0 2 4 6 8 1 3 5 7 9) at: x digitValue + 1]. >> (oddSum + evenSum) \\ 10 = 0]] >> >> This is the kind of code I was recommending that Roelof write. >> >> As a rough guide, by counting traversals (including ones inside >existing >> methods), I'd expect the "high level" code to be at least 10 times >slower >> than the "no added slowness" code. >> >> We are in vehement agreement that there is a time to write high level >> really obvious easily testable and debuggable code, and that's most >> of the time, especially with programming exercises. >> >> I hope that we are also in agreement that factors of 30 (or even 6) >> *can* be a serious problem. I mean, if I wanted something that slow, >> I'd use Ruby. >> >> I hope we are also agreed that (with the exception of investigations >> like this one) the time to hack on something to make it faster is >AFTER >> you have profiled it and determined that you have a problem. >> >> But I respectfully suggest that there is a difference taking slowness >OUT >> and simply not going out of your way to add slowness in the first >place. >> >> I'd also like to remark that my preference for methods that traverse >a >> sequence exactly once has more to do with Smalltalk protocols than >> with efficiency. If the only method I perform on an object is #do: >> the method will work just as well for readable streams as for >> collections. If the only method I perform on an object is >#reverseDo: >> the method will work just as well for Read[Write]Streams as for >> SequenceReadableCollections, at least in my library. It's just like >> trying to write #mean so that it works for Durations as well as >Numbers. >> >> Oh heck, I suppose I should point out that much of the overheads in >> this case could be eliminated by a Self-style compiler doing dynamic >> inlining + loop fusion. There's no reason *in principle*, given >enough >> people, money, and time, that the differences couldn't be greatly >> reduced in Pharo. >> >> On Tue, 5 May 2020 at 21:50, Trygve Reenskaug <trygver(a)ifi.uio.no> >wrote: >> >> >> Richard, >> >> Thank you for looking at the code. It is comforting to learn that the >code has been executed for a large number of examples without breaking. >The code is not primarily written for execution but for being read and >checked by the human end user. It would be nice if we could also check >that it gave the right answers, but I don't know how to do that. >> >> The first question is: Can a human domain expert read the code and >sign their name for its correctness? >> >> >> When this is achieved, a programming expert will transcribe the first >code to a professional quality program. This time, the second code >should be reviewed by an independent programmer who signs their name >for its correct transcription from the first version. >> >> --Trygve >> >> PS: In his 1991 Turing Award Lecture, Tony Hoare said: "There are two >ways of constructing a software design: One way is to make it so simple >that there are obviously no deficiencies and the other is to make it so >complicated that there are no obvious deficiencies. The first method is >far more difficult." >> >> --Trygve >> >> On tirsdag.05.05.2020 04:41, Richard O'Keefe wrote: >> >> As a coding experiment, I adapted Trygve Reenskoug's code to my >> Smalltalk compiler, put in my code slightly tweaked, and benchmarked >> them on randomly generated data. >> >> Result: a factor of 6.3. >> >> In Squeak it was a factor of ten. >> >> I had not, in all honesty, expected it to to be so high. >> >> On Tue, 5 May 2020 at 02:00, Trygve Reenskaug <trygver(a)ifi.uio.no> >wrote: >> >> A coding experiment. >> Consider a Scrum development environment. Every programming team has >an end user as a member. >> The team's task is to code a credit card validity check. >> A first goal is that the user representative shall read the code and >agree that it is a correct rendering of their code checker: >> >> luhnTest: trialNumber >> | s1 odd s2 even charValue reverse | >> ----------------------------------------------- >> " Luhn test according to Rosetta" >> "Reverse the order of the digits in the number." >> reverse := trialNumber reversed. >> "Take the first, third, ... and every other odd digit in the reversed >digits and sum them to form the partial sum s1" >> s1 := 0. >> odd := true. >> reverse do: >> [:char | >> odd >> ifTrue: [ >> s1 := s1 + char digitValue. >> ]. >> odd := odd not >> ]. >> "Taking the second, fourth ... and every other even digit in the >reversed digits: >> Multiply each digit by two and sum the digits if the answer is >greater than nine to form partial sums for the even digits" >> "The subtracting 9 gives the same answer. " >> "Sum the partial sums of the even digits to form s2" >> s2 := 0. >> even := false. >> reverse do: >> [:char | >> even >> ifTrue: [ >> charValue := char digitValue * 2. >> charValue > 9 ifTrue: [charValue := charValue - >9]. >> s2 := s2 + charValue >> ]. >> even := even not >> ]. >> "If s1 + s2 ends in zero then the original number is in the form of a >valid credit card number as verified by the Luhn test." >> ^(s1 + s2) asString last = $0 >> --------------------------------- >> Once this step is completed, the next step will be to make the code >right without altering the algorithm (refactoring). The result should >be readable and follow the team's conventions. >> >> >> P.S. code attached. >> >> >> -- >> >> The essence of object orientation is that objects collaborate to >achieve a goal. >> Trygve Reenskaug mailto: trygver(a)ifi.uio.no >> Morgedalsvn. 5A http://folk.uio.no/trygver/ >> N-0378 Oslo http://fullOO.info >> Norway Tel: (+47) 468 58 625 >> >> >> >> -------------------------------------------- >> StÃ©phane Ducasse >> http://stephane.ducasse.free.fr / http://www.pharo.org >> 03 59 35 87 52 >> Assistant: Julie Jonas >> FAX 03 59 57 78 50 >> TEL 03 59 35 86 16 >> S. Ducasse - Inria >> 40, avenue Halley, >> Parc Scientifique de la Haute Borne, BÃ¢t.A, Park Plaza >> Villeneuve d'Ascq 59650 >> France >>

May 11, 2020

Re: [Pharo-users] mentor question 4

by Richard O'Keefe

I was saying that I expected #($a $b $c) asString ==> 'abc'. If you want something that can be read back, that's what #storeString is for, On Tue, 12 May 2020 at 01:28, StÃ©phane Ducasse <stephane.ducasse(a)inria.fr> wrote: > > > > On 5 May 2020, at 16:16, Richard O'Keefe <raoknz(a)gmail.com> wrote: > > By the way, while playing with this problem, I ran into a moderately > painful issue. > > There is a reason that Smalltalk has both #printString (to get a > printable representation of an object) and #asString (to convert a > sequence to another kind of sequence with the same elements.) If I > *want* #printString, I know where to find it. The definition in my > Smalltalk no reads > > asString > "What should #($a $b $c) do? > - Blue Book, Inside Smalltalk, Apple Smalltalk-80: > there is no #asString. > - ANSI, VW, Dolphin, CSOM: > #asString is defined on characters and strings > (and things like file names and URIs that are sort of strings), > so expect an error report. > - VisualAge Smalltalk: > '($a $b $c)' > - Squeak and Pharo: > '#($a $b $c)' > - GNU Smalltalk, Smalltalk/X, and astc: > 'abc' > I don't intend any gratuitous incompatibility, but when there > is no consensus to be compatible with, one must pick something, > and this seems most useful. > " > ^String withAll: self > > Does anyone here know WHY Squeak and Pharo do what they do here? > > > Oops I did not see the quotes on my screen.. > > #( a b c) asString > >>> '#(#a #b #c)â > > this is unclear to me why this is not good but I have no strong opinion > that this is good. > > I worked on printString for literals because I wanted to have > self evaluating properties for basic literal like in Scheme and others. > where > #t > >>> > #t > > And I payed attention that we get the same for literal arrays. > Now the conversion is open to me. > > #($a $b $c) asString > >>> > '#($a $b $c)â > > In fact I do not really understand why a string > > #($a $b $c) asString would be '(a b c)â > and its use > if this is to nicely display in the ui I would have > displayString doing it. > > S. > > > > On Wed, 6 May 2020 at 01:20, Richard O'Keefe <raoknz(a)gmail.com> wrote: > > > The irony is that the code I was responding to ISN'T obviously correct. > Indeed, I found it rather puzzling. > The problem specification says that the input string may contain digits > AND SPACES. The original message includes this: > > Strings of length 1 or less are not valid. Spaces are allowed in the > input, but they should be stripped before checking. All other > non-digit characters are disallowed. > > Now it isn't clear what "disallowed" means. I took it to mean "may occur and > should simply mean the input is rejected as invalid." Perhaps "may not occur" > was the intention. So we shall not quibble about such characters. > > But I can't for the life of me figure out how Trygve's code checks for spaces. > One reason this is an issue is that the behaviour of #digitValue is not > consistent between systems. > Character space digitValue > does not exist in the ANSI standard > answers -1 in many Smalltalks (which is a pain) > answers a positive integer that can't be mistake for a digit in my Smalltalk > raises an exception in some Smalltalks. > > This is a comment I now have in my Smalltalk library for #digitValue > "This is in the Blue Book, but unspecified on non-digits. > Squeak, Pharo, Dolphin, VW, VAST, and Apple Smalltalk-80 > answer -1 for characters that are not digits (or ASCII letters), > which is unfortunate but consistent with Inside Smalltalk > which specifies this result for non-digits. > ST/X and GST raise an exception which is worse. > Digitalk ST/V documentation doesn't specify the result. > This selector is *much* easier to use safely if it > returns a 'large' (>= 36) value for non-digits." > > Let's compare three versions, the two I compared last time, > and the "version A" code I discussed before, which to my mind > is fairly readable. > > "Don't add slowness": 1 (normalised time) > "Trygve's code": 6.5 > "High level code": 30.6 (or 4.7 times slower than Trygve's) > > Here's the "High level code". > ^(aString allSatisfy: [:each | each isSpace or: [each isDigit]]) and: [ > |digitsReverse| > digitsReverse := (aString select: [:each | each isDigit]) reverse. > digitsReverse size > 1 and: [ > |evens odds evenSum oddSum| > odds := digitsReverse withIndexSelect: [:y :i | i odd]. > evens := digitsReverse withIndexSelect: [:x :i | i even]. > oddSum := odds detectSum: [:y | y digitValue]. > evenSum := evens detectSum: [:x | > #(0 2 4 6 8 1 3 5 7 9) at: x digitValue + 1]. > (oddSum + evenSum) \\ 10 = 0]] > > This is the kind of code I was recommending that Roelof write. > > As a rough guide, by counting traversals (including ones inside existing > methods), I'd expect the "high level" code to be at least 10 times slower > than the "no added slowness" code. > > We are in vehement agreement that there is a time to write high level > really obvious easily testable and debuggable code, and that's most > of the time, especially with programming exercises. > > I hope that we are also in agreement that factors of 30 (or even 6) > *can* be a serious problem. I mean, if I wanted something that slow, > I'd use Ruby. > > I hope we are also agreed that (with the exception of investigations > like this one) the time to hack on something to make it faster is AFTER > you have profiled it and determined that you have a problem. > > But I respectfully suggest that there is a difference taking slowness OUT > and simply not going out of your way to add slowness in the first place. > > I'd also like to remark that my preference for methods that traverse a > sequence exactly once has more to do with Smalltalk protocols than > with efficiency. If the only method I perform on an object is #do: > the method will work just as well for readable streams as for > collections. If the only method I perform on an object is #reverseDo: > the method will work just as well for Read[Write]Streams as for > SequenceReadableCollections, at least in my library. It's just like > trying to write #mean so that it works for Durations as well as Numbers. > > Oh heck, I suppose I should point out that much of the overheads in > this case could be eliminated by a Self-style compiler doing dynamic > inlining + loop fusion. There's no reason *in principle*, given enough > people, money, and time, that the differences couldn't be greatly > reduced in Pharo. > > On Tue, 5 May 2020 at 21:50, Trygve Reenskaug <trygver(a)ifi.uio.no> wrote: > > > Richard, > > Thank you for looking at the code. It is comforting to learn that the code has been executed for a large number of examples without breaking. The code is not primarily written for execution but for being read and checked by the human end user. It would be nice if we could also check that it gave the right answers, but I don't know how to do that. > > The first question is: Can a human domain expert read the code and sign their name for its correctness? > > > When this is achieved, a programming expert will transcribe the first code to a professional quality program. This time, the second code should be reviewed by an independent programmer who signs their name for its correct transcription from the first version. > > --Trygve > > PS: In his 1991 Turing Award Lecture, Tony Hoare said: "There are two ways of constructing a software design: One way is to make it so simple that there are obviously no deficiencies and the other is to make it so complicated that there are no obvious deficiencies. The first method is far more difficult." > > --Trygve > > On tirsdag.05.05.2020 04:41, Richard O'Keefe wrote: > > As a coding experiment, I adapted Trygve Reenskoug's code to my > Smalltalk compiler, put in my code slightly tweaked, and benchmarked > them on randomly generated data. > > Result: a factor of 6.3. > > In Squeak it was a factor of ten. > > I had not, in all honesty, expected it to to be so high. > > On Tue, 5 May 2020 at 02:00, Trygve Reenskaug <trygver(a)ifi.uio.no> wrote: > > A coding experiment. > Consider a Scrum development environment. Every programming team has an end user as a member. > The team's task is to code a credit card validity check. > A first goal is that the user representative shall read the code and agree that it is a correct rendering of their code checker: > > luhnTest: trialNumber > | s1 odd s2 even charValue reverse | > ----------------------------------------------- > " Luhn test according to Rosetta" > "Reverse the order of the digits in the number." > reverse := trialNumber reversed. > "Take the first, third, ... and every other odd digit in the reversed digits and sum them to form the partial sum s1" > s1 := 0. > odd := true. > reverse do: > [:char | > odd > ifTrue: [ > s1 := s1 + char digitValue. > ]. > odd := odd not > ]. > "Taking the second, fourth ... and every other even digit in the reversed digits: > Multiply each digit by two and sum the digits if the answer is greater than nine to form partial sums for the even digits" > "The subtracting 9 gives the same answer. " > "Sum the partial sums of the even digits to form s2" > s2 := 0. > even := false. > reverse do: > [:char | > even > ifTrue: [ > charValue := char digitValue * 2. > charValue > 9 ifTrue: [charValue := charValue - 9]. > s2 := s2 + charValue > ]. > even := even not > ]. > "If s1 + s2 ends in zero then the original number is in the form of a valid credit card number as verified by the Luhn test." > ^(s1 + s2) asString last = $0 > --------------------------------- > Once this step is completed, the next step will be to make the code right without altering the algorithm (refactoring). The result should be readable and follow the team's conventions. > > > P.S. code attached. > > > -- > > The essence of object orientation is that objects collaborate to achieve a goal. > Trygve Reenskaug mailto: trygver(a)ifi.uio.no > Morgedalsvn. 5A http://folk.uio.no/trygver/ > N-0378 Oslo http://fullOO.info > Norway Tel: (+47) 468 58 625 > > > > -------------------------------------------- > StÃ©phane Ducasse > http://stephane.ducasse.free.fr / http://www.pharo.org > 03 59 35 87 52 > Assistant: Julie Jonas > FAX 03 59 57 78 50 > TEL 03 59 35 86 16 > S. Ducasse - Inria > 40, avenue Halley, > Parc Scientifique de la Haute Borne, BÃ¢t.A, Park Plaza > Villeneuve d'Ascq 59650 > France >

May 11, 2020

Need help putting my Pharo package under source control

by Michael Burns

I read the section in 2018-09-29-UPDATEDPHAROBYEXAMPLE: "Monticello packagesâ just after Figure 3-27 I have a smalltalkhub account and created a repository: MCHttpRepository location: 'http://smalltalkhub.com/mc/MichaelKentBurns/FredsLunch/main' user: '' password: â' In Pharo I registered this as a new smalltalkhub repository: 'http://smalltalkhub.com/mc/MichaelKentBurns/FredsLunch/mainâ And it shows up in the repository list for my package. Then I think Iâm supposed to poke âSaveâ. It was kind of sketchy and popped up exception dialogs while I was typing my comment, but eventually it worked. I was able to download the resultant .mcz file and unzip it, then change the ^M to newlines to get a readable source. Iâm not really happy about this process. I would like to actually save this into my GitHub repository. The document mentioned at the top mentions using git, but just says: There is a chapter in preparation on how to use Git with Pharo. Request it on the Pharo mailing list. Question 1: Is there such a document? If so, can you point me to it? Question 2: Is there a way to fileOut a class, or a package?

May 11, 2020