April 2019 - Pharo-users - lists.pharo.org

Re: [Pharo-users] how to model this a better way

by Ben Coman

On Wed, 24 Apr 2019 at 16:52, Richard O'Keefe <raoknz(a)gmail.com> wrote: > The one method needed to solve the problem is 18 lines. > The test code, including all available test cases, is 27 > lines, of which 18 lines is the test data. Tests were > needed primarily to sort out what the problem actually *was*; > exercism doesn't even try to provide good specifications. > No debugging time at all was needed, precisely because the > code was so simple and obvious. But we do want to showcase our debugger and demonstrate how to get the most out of it. The way the exercises are structured is to sequentially enable one test at a time, see how that fails and fix it, so students will be regularly interacting with debugger. > If it *had* been needed, > viewing the result right next to the expression that yielded > it would have given me all the context I needed, in one window. > > If you want to learn how to design a good set of classes, > this is an absolutely dreadful problem. In fact ALL of the > exercism problems are going to be dreadful for *that* > purpose because they are provided for languages that do not > *have* classes. Yes, we noticed that. Do you have any problems more suited to class creation that we might contribute to the Exercism problem specifications? > If you want to learn how to *solve problems*, > then you need to learn to write code that is simple, clear, > testable, and so on. You certainly need to learn how to use > what is already there in the language (except where that is > expressly forbidden). My understanding of the Exercism's purpose is: * not to teach how to solve programming problems; but * to facilitate existing programmers to develop fluency in new languages (although that doesn't preclude complete beginners using it). [ref: search "fluency" at https://opensource.com/article/17/1/interview-katrina-owen-founder-exercism] > I completely agree that designing a good set of classes is > a very very important skill for anyone who wants to do OOP. > I completely agree that practising this on problems you can > hold in your head is a good idea. > I completely agree that if *that* is your objective, > writing minimalist code is not the best strategy. >On Wed, 24 Apr 2019 at 16:59, Richard O'Keefe <raoknz(a)gmail.com> wrote: >> >> TL;DR version: >> "But if the purpose of problems is to lead students in new ways of >> thinking about structuring OO solutions for maintainability" >> It would be very good >> if somebody did craft such a set of exercises, and Pharo would be a very >> good environment for them. The exercism exercises will not do. If the existing set of exercises is not great for this, hopefully we can produce some to demonstrate Pharo's facility for it. > The problem with exercism is that while it does have a > criterion by which you can tell whether you have *solved the > problem*, it provides *no* way to assess your class design. > You don't get told "this is good, that is bloated"; there is > no feedback about the *quality* of your code except via > comments from those few people who can be bothered to look > at other people's solutions and comment on them. And since > many of them will also be beginners, their comments may not > always help. Hopefully we can grow participation of experienced mentors to share the load providing *quality* feedback to distinguish the benefits of Pharo. > This particular problem is very similar to a "Langton's Ant" > problem my old department gave to students, who were expected > to solve it in two or three hours. And ALWAYS, the thing that > held them back was creating classes they didn't need and > agonising over what data and methods should go where (and then > getting it wrong, such is the nature of Java). My immediate reaction to that is that agonizing and getting it wrong are a useful part of the learning process, but I recognize I could just be being contrary :) . I'll keep your observations in mind. > > When a problem can be solved quite directly in 18 lines of > clean code, you are going to have a very hard time persuading > me that even one more class pays for itself, especially in a > system with a rich class library of stuff you don't have to write. Not trying to persuade you personally. Just providing an alternative viewpoint for anyone to consider. cheers -ben

April 24, 2019

Re: [Pharo-users] OneClick image

by Noury Bouraqadi

Thanks Esteban and Vincent. > On 24 Apr 2019, at 10:19, <vincent.blondeau(a)polytech-lille.net> <vincent.blondeau(a)polytech-lille.net> wrote: > > Hi Noury, > > Last year there was such an initiative that has been launched to package Pharo apps: https://github.com/VincentBlondeau/Cruiser > It is supporting only windows for now, but it planned to be enhanced for other platforms. It is not on my priorities list yet, but I will work on it again for sure. > > HTH > > Cheers, > Vincent > > > -----Original Message----- > From: Pharo-users <pharo-users-bounces(a)lists.pharo.org> On Behalf Of Esteban Lorenzano > Sent: Wednesday, 24 April 2019 09:57 > To: Any question about pharo is welcome <pharo-users(a)lists.pharo.org> > Subject: Re: [Pharo-users] OneClick image > > Hi, > > It never worked for Pharo, because is more intended to applications (it was developed for Sofie). > So we replaced it with the platform distributions (one zip for platform) and the one-click became the âportableâ version, but this approach also didnât work and thatâs why we ended with the Pharo Launcher as recommended download, zeroconf for CI and the âindependent downloadsâ as needed. > > If you still want it, you can do one by yourself taking one of the historic portables as base: http://files.pharo.org/platform/Pharo6.1-portable.zip > > You will need to update VMs and that but in general, it should work. > > Esteban > >> On 24 Apr 2019, at 09:04, N. Bouraqadi <bouraqadi(a)gmail.com> wrote: >> >> Hi, >> >> Few years ago, there was a zip file called 'oneclick' that included everything to run Pharo on all 3 major OSes. All one had to do is unzip it, and launch a script that opens the image. >> >> What happen to that? Any idea why it isn't generated anymore? >> >> Noury > > > >

April 24, 2019

Pharo 7.0.3 dialog information at startup

by Trussardi Dario Romano

Ciao, i download the last Pharo 70 image ( on Ubuntu 16.04 LTS system ) with the commannd: wget -O- https://get.pharo.org/64/70+vm | bash When i launch the relative ./pharo-ui after the opening the Pharo window the Pharo system open an information with: Information Cannot read stored value of #pharoSystem#delaySchedulerClass. Exception: KeyNotFound: key #DelaySpinScheduler not found in SystemDictionary Should i consider it as an important problem or can i proceed ignoring it? Thanks, Dario

April 24, 2019

Re: [Pharo-users] how to model this a better way

by Richard O'Keefe

TL;DR version: "But if the purpose of problems is to lead students in new ways of thinking about structuring OO solutions for maintainability" That is not the purpose of the exercism problems. It would be very good if somebody did craft such a set of exercises, and Pharo would be a very good environment for them. The exercism exercises will not do. Betrand Meyer has an OOP course that gets students started *modifying* a non-trivial program, a traffic simulator I believe, instead of writing free-standing toy programs. Worth thinking about. On Wed, 24 Apr 2019 at 04:58, Ben Coman <btc(a)openinworld.com> wrote: > On Mon, 22 Apr 2019 at 23:15, Richard O'Keefe <raoknz(a)gmail.com> wrote: > > > > I already discoursed on this at some length. > > (1) In my own answer, I used code to map direction names to vectors. > > But the Dictionary answers are absolutely fine. > > (2) I pointed out that there are ALREADY "turn left" and "turn right" > > operations on Points. > > (3) An elegant solution is one which wastes no effort. > > Introducing classes that you don't need is definitely wasted > > effort. > > Elegance in art is in the eye of the beholder. You've got one position on > it. > I'll just balance it with an alternative view for students to consider > around "classes that you don't need". > > > WARNING: untested first draft code (can't find the tested stuff). > > obey: commands > > |position direction| > > position := 0@0. > > direction := 1@0. > > commands do: [:each | > > each caseOf: { > > [$A] -> [position := position + direction]. > > [$L] -> [direction := direction leftRotated]. > > [$R] -> [direction := direction rightRotated] > > }]. > > ^{position. direction} > > You will need to fiddle with this a bit to get the mapping between > > problem coordinates and solution coordinates right, and you'll > > need that Dictionary mapping directions to direction names, but > > that's pretty much it. > > > If you define more than one class for this problem, your code is not > elegant. > > If the purpose of the problems is simply to solve the problem, then > doing the absolute minimum is a reasonable view of elegance. > After all, its throw away code. You're never going to be maintaining it. > > But if the purpose of problems is to lead students in new ways of > thinking about structuring OO solutions > for maintainability within Pharo, then I feel its lacking. I remember > an instructor from my youth > advising that "practicing a kata poorly is the habit that will be > reproduced automatically (in a crisis)" > > > ^{position. direction} > > For me, viewing {2@3. 1@0 } in a debugger is a much greater > cognitive load than {2@3. 'Facing east'} > to determine which direction its facing. So I consider the latter > more elegant. TDD helps minimise class over-engineering, > but for me the latter is a "need". In terms of throw-away exercises, > its about what habits students want to gain from doing them. > > Just another perspective. > cheers -ben > >

April 24, 2019

Re: [Pharo-users] how to model this a better way

by Richard O'Keefe

Let me tell you a story. The story is about someone I knew back when I was doing my MSc. He was really bright, but he had to repeat a year in the papers part of his MSc. Why? Because he didn't get statistics. Differential equations? No problem. Topology? No problem. Operations research (which was his actual topic)? A walk in the park. Statistics? He just couldn't get it. Why not? "I read the book, and I think I understand, and then I come to the examples, and I can't see why they use the method they use, why that is a good method for that problem." I hope it made a difference to him when I replied "You can't see why method X is a good choice for problem Y because it isn't. If your goal is to illustrate the workings of method X, problem Y will do. But if your goal is to actually solve problem Y, method X is the last thing you should try." I actually worked through a couple of famous textbooks, example by example, and found that for more than half of the problems, if you followed the advice in the book about how to select a method, you would never select the method in the example, and the method you would select instead gave better and on occasion much better results. In this particular case, I don't give a damn about what {1@0. 0@} looks like in a debugger, BECAUSE IT NEVER DID APPEAR IN A DEBUGGER. The one method needed to solve the problem is 18 lines. The test code, including all available test cases, is 27 lines, of which 18 lines is the test data. Tests were needed primarily to sort out what the problem actually *was*; exercism doesn't even try to provide good specifications. No debugging time at all was needed, precisely because the code was so simple and obvious. If it *had* been needed, viewing the result right next to the expression that yielded it would have given me all the context I needed, in one window. If you want to learn how to design a good set of classes, this is an absolutely dreadful problem. In fact ALL of the exercism problems are going to be dreadful for *that* purpose because they are provided for languages that do not *have* classes. If you want to learn how to *solve problems*, then you need to learn to write code that is simple, clear, testable, and so on. You certainly need to learn how to use what is already there in the language (except where that is expressly forbidden). I completely agree that designing a good set of classes is a very very important skill for anyone who wants to do OOP. I completely agree that practising this on problems you can hold in your head is a good idea. I completely agree that if *that* is your objective, writing minimalist code is not the best strategy. The problem with exercism is that while it does have a criterion by which you can tell whether you have *solved the problem*, it provides *no* way to assess your class design. You don't get told "this is good, that is bloated"; there is no feedback about the *quality* of your code except via comments from those few people who can be bothered to look at other people's solutions and comment on them. And since many of them will also be beginners, their comments may not always help. This particular problem is very similar to a "Langton's Ant" problem my old department gave to students, who were expected to solve it in two or three hours. And ALWAYS, the thing that held them back was creating classes they didn't need and agonising over what data and methods should go where (and then getting it wrong, such is the nature of Java). When a problem can be solved quite directly in 18 lines of clean code, you are going to have a very hard time persuading me that even one more class pays for itself, especially in a system with a rich class library of stuff you don't have to write. "You Aren't Gunna Need It" is a good slogan. "If you didn't write it you didn't wrong it" is another.

April 24, 2019

Re: [Pharo-users] OneClick image

by vincent.blondeau＠polytech-lille.net

Hi Noury, Last year there was such an initiative that has been launched to package Pharo apps: https://github.com/VincentBlondeau/Cruiser It is supporting only windows for now, but it planned to be enhanced for other platforms. It is not on my priorities list yet, but I will work on it again for sure. HTH Cheers, Vincent -----Original Message----- From: Pharo-users <pharo-users-bounces(a)lists.pharo.org> On Behalf Of Esteban Lorenzano Sent: Wednesday, 24 April 2019 09:57 To: Any question about pharo is welcome <pharo-users(a)lists.pharo.org> Subject: Re: [Pharo-users] OneClick image Hi, It never worked for Pharo, because is more intended to applications (it was developed for Sofie). So we replaced it with the platform distributions (one zip for platform) and the one-click became the âportableâ version, but this approach also didnât work and thatâs why we ended with the Pharo Launcher as recommended download, zeroconf for CI and the âindependent downloadsâ as needed. If you still want it, you can do one by yourself taking one of the historic portables as base: http://files.pharo.org/platform/Pharo6.1-portable.zip You will need to update VMs and that but in general, it should work. Esteban > On 24 Apr 2019, at 09:04, N. Bouraqadi <bouraqadi(a)gmail.com> wrote: > > Hi, > > Few years ago, there was a zip file called 'oneclick' that included everything to run Pharo on all 3 major OSes. All one had to do is unzip it, and launch a script that opens the image. > > What happen to that? Any idea why it isn't generated anymore? > > Noury

April 24, 2019

Re: [Pharo-users] OneClick image

by Esteban Lorenzano

Hi, It never worked for Pharo, because is more intended to applications (it was developed for Sofie). So we replaced it with the platform distributions (one zip for platform) and the one-click became the âportableâ version, but this approach also didnât work and thatâs why we ended with the Pharo Launcher as recommended download, zeroconf for CI and the âindependent downloadsâ as needed. If you still want it, you can do one by yourself taking one of the historic portables as base: http://files.pharo.org/platform/Pharo6.1-portable.zip You will need to update VMs and that but in general, it should work. Esteban > On 24 Apr 2019, at 09:04, N. Bouraqadi <bouraqadi(a)gmail.com> wrote: > > Hi, > > Few years ago, there was a zip file called 'oneclick' that included everything to run Pharo on all 3 major OSes. All one had to do is unzip it, and launch a script that opens the image. > > What happen to that? Any idea why it isn't generated anymore? > > Noury

April 24, 2019

OneClick image

by N. Bouraqadi

Hi, Few years ago, there was a zip file called 'oneclick' that included everything to run Pharo on all 3 major OSes. All one had to do is unzip it, and launch a script that opens the image. What happen to that? Any idea why it isn't generated anymore? Noury

April 24, 2019

Re: [Pharo-users] how to model this a better way

by Ben Coman

On Mon, 22 Apr 2019 at 23:15, Richard O'Keefe <raoknz(a)gmail.com> wrote: > > I already discoursed on this at some length. > (1) In my own answer, I used code to map direction names to vectors. > But the Dictionary answers are absolutely fine. > (2) I pointed out that there are ALREADY "turn left" and "turn right" > operations on Points. > (3) An elegant solution is one which wastes no effort. > Introducing classes that you don't need is definitely wasted > effort. Elegance in art is in the eye of the beholder. You've got one position on it. I'll just balance it with an alternative view for students to consider around "classes that you don't need". > WARNING: untested first draft code (can't find the tested stuff). > obey: commands > |position direction| > position := 0@0. > direction := 1@0. > commands do: [:each | > each caseOf: { > [$A] -> [position := position + direction]. > [$L] -> [direction := direction leftRotated]. > [$R] -> [direction := direction rightRotated] > }]. > ^{position. direction} > You will need to fiddle with this a bit to get the mapping between > problem coordinates and solution coordinates right, and you'll > need that Dictionary mapping directions to direction names, but > that's pretty much it. > If you define more than one class for this problem, your code is not elegant. If the purpose of the problems is simply to solve the problem, then doing the absolute minimum is a reasonable view of elegance. After all, its throw away code. You're never going to be maintaining it. But if the purpose of problems is to lead students in new ways of thinking about structuring OO solutions for maintainability within Pharo, then I feel its lacking. I remember an instructor from my youth advising that "practicing a kata poorly is the habit that will be reproduced automatically (in a crisis)" > ^{position. direction} For me, viewing {2@3. 1@0 } in a debugger is a much greater cognitive load than {2@3. 'Facing east'} to determine which direction its facing. So I consider the latter more elegant. TDD helps minimise class over-engineering, but for me the latter is a "need". In terms of throw-away exercises, its about what habits students want to gain from doing them. Just another perspective. cheers -ben

April 23, 2019

Re: [Pharo-users] Gettext

by Norbert Hartl

Just for the record. This is the repo we had before in the zweidenker repo. I transferred it to pharo-contributions. So if you use this repository you should update your metacello to reflect to new location. Any, thanks very much, Pavel, for taking the initiative. Gettext definitely needs some love and we didnât find time so far. Norbert > Am 23.04.2019 um 13:31 schrieb Pavel Krivanek <pavel.krivanek(a)gmail.com>: > > Hi, > > I made some little tweaks on the Gettext project and I wrote few lines of documentation about it: > > https://github.com/pharo-contributions/Gettext <https://github.com/pharo-contributions/Gettext> > > Feel free to contribute if it may be interesting for your applications. Notice that I am not the original author of this project, I'm just passing by ;-) > > Cheers, > -- Pavel >

April 23, 2019