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

Re: [Pharo-users] Transforming objects
by Richard O'Keefe Jan. 20, 2019

Jan. 20, 2019

I note that #become: is not in the ANSI Smalltalk standard (am I the last person in the world to care about that? Probably) and that several of the Smalltalk systems I have on my machine don't support it. In Squeak 5.2, there were 17 references to #become:. Four of those were just testing it. One is just a mention in a collection of dangerous things to not be tried. Several are ways of changing an object's class. Several are ways of forcibly deleting an object by turning it into something trivial but safe. And a couple, I don't understand. Thing is, #become: is *not* something to do lightly, and the code that calls "x become: y" should "own" both x and y. (In fact one of them is often "self".) About The Design Patterns Smalltalk Companion, draft chapters are available at http://sdmeta.gforge.inria.fr/FreeBooks/SmalltalkDesignPatternCompanion/ When I read the Gang of Four book, it seemed to me that most of it was about fighting the fact that C++ and Java aren't Smalltalk. Read a draft chapter or two to make up your own mind. One difference between the State pattern and #become: is that an object can be an instance of the State pattern in more than one way at the same time. On Thu, 17 Jan 2019 at 05:58, Ben Coman via Pharo-users < pharo-users(a)lists.pharo.org> wrote: > > > On Wed, 16 Jan 2019 at 17:16, LoÃ¯c PagÃ¨s <loic.pages(a)inra.fr> wrote: > >> Dear Pharo users, >> >> I develop software dedicated to the simulation of plant development and >> 3D architecture. >> >> In the past, I used Java, > > but I am very interested in translating code >> in Pharo. I appreciated very much the language and the course. >> >> I have a question for you all : >> >> During plant development (ontogeny), new organs appear, that are >> gradually tranformed. For example, a bud can make a flower, and then a >> fruit. >> >> Organs are conveniently modelled as classes. During the course, I >> learned that it was better to make several classes (bud, flower, fruit) >> instead of a "fat class" such as "reproductive organ" with many >> attributes and stages (bud stage, flower stage, fruit stage). I wonder >> how to transform an object into another one, to represent for example >> the fact that the flower may become a fruit. >> >> Maybe a naive question ? >> > > Maybe #become: ... > https://gbracha.blogspot.com/2009/07/miracle-of-become.html > > but it might be a misuse for your purpose. The following book will > provide some good insights... > https://www.amazon.com/Design-Patterns-Smalltalk-Companion/dp/0201184621 > > cheers -ben > > > >

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Re: [Pharo-users] Limits of ZnManagingMultiThreadedServer
by Stephan Eggermont Jan. 18, 2019

Jan. 18, 2019

Ah, found another consumer of sockets :). For reliable systems, putting limits on the number of retries seems a useful idea. Thanks Sven, Stephan

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[ Save The Date ] Pharo Days 2019: Thursday April 4 & Friday April 5 @ Lille, FR
by Sven Van Caekenberghe Jan. 18, 2019

Jan. 18, 2019

[ Save The Date ] Pharo Days 2019: Thursday April 4 & Friday April 5 @ Lille, FR Dear members of the Pharo community, We are happy to announce that we will be organising Pharo Days this year, in Lille, France. This will be a two day event: Thursday April 4 & Friday April 5. The main venue will be the Amphitheatre of INRIA Lille - Nord Europe. Each day will consist of a number of short 20 to 30 minutes tech talks in the morning, with a more free format in the afternoon: general hacking space, pair programming, demos, side meetings, tutorials, coding sprints, Q&A's, shows us your projects - real life human interaction. Of course, there will be social events as well. Please join us to make this another successful edition, after Annecy (FR) 2011, Lille 2012, Bern (CH) & Lille 2013, Lille 2015, Namur (BE) 2016 and Lille 2017. Mark your calendars, we will provide more details when they become available. The Pharo Board, Association & Consortium http://pharo.org http://association.pharo.org http://consortium.pharo.org

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Re: [Pharo-users] Limits of ZnManagingMultiThreadedServer
by Sven Van Caekenberghe Jan. 18, 2019

Jan. 18, 2019

Hi Stephan, > On 18 Jan 2019, at 14:03, Stephan Eggermont via Pharo-users <pharo-users(a)lists.pharo.org> wrote: > > > From: Stephan Eggermont <stephan(a)stack.nl> > Subject: Limits of ZnManagingMultiThreadedServer > Date: 18 January 2019 at 14:03:43 GMT+1 > To: pharo-users(a)lists.pharo.org > > > I have a few images connecting regularly to a server using ZnEasy get: on > windows 64 bit and a recent vm and Pharo 7 image. At a certain point, the > server stops with âCreateThread() failed (1450) - Insufficient system > resources exist to complete the requested service. > > I probably should switch to keeping connections open and avoid this > problem, but it made me wonder about the limitations I should expect here. > What are the limits here and can I change them? > > Stephan I am not sure I understand correctly: does the error occur on the client or server side (assuming they are both written in Pharo using Zinc HTTP Components). Because 'CreateThread() failed (1450) - Insufficient system resources exist to complete the requested service' does not sound like a Pharo error. In any case, ZnEasy class>>#get: uses #beOneShot so that the client side connection is closed after 1 request, it also uses the Connection:close header so that the server knows it does not have to keep the connection open. Server side, Zn should also clean up nicely (even for dirty requests). But is also depends on what you do inside your server side request handler. Maybe something prevents normal GC to clean up ? Although Pharo processes are like green threads (not OS threads) you can technically use too many. Typically you will run out of sockets for IO. Unless you have a a real leak, it might be a GC configuration problem: a little used server might not invoke enough real/full GC cycles. In any case, I have many images with long running HTTP servers and clients and I don't have any issues. How many requests are we talking about, how many concurrent users, how long before things go wrong ? Sven

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Limits of ZnManagingMultiThreadedServer
by Stephan Eggermont Jan. 18, 2019

Jan. 18, 2019

I have a few images connecting regularly to a server using ZnEasy get: on windows 64 bit and a recent vm and Pharo 7 image. At a certain point, the server stops with âCreateThread() failed (1450) - Insufficient system resources exist to complete the requested service. I probably should switch to keeping connections open and avoid this problem, but it made me wonder about the limitations I should expect here. What are the limits here and can I change them? Stephan

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Transforming objects
by LoÃ¯c PagÃ¨s Jan. 17, 2019

Jan. 17, 2019

Dear Pharo users, I develop software dedicated to the simulation of plant development and 3D architecture. In the past, I used Java, but I am very interested in translating code in Pharo. I appreciated very much the language and the course. I have a question for you all : During plant development (ontogeny), new organs appear, that are gradually tranformed. For example, a bud can make a flower, and then a fruit. Organs are conveniently modelled as classes. During the course, I learned that it was better to make several classes (bud, flower, fruit) instead of a "fat class" such as "reproductive organ" with many attributes and stages (bud stage, flower stage, fruit stage). I wonder how to transform an object into another one, to represent for example the fact that the flower may become a fruit. Maybe a naive question ? Thanks for your lights ! LoÃ¯c

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Smalltalks 2018 videos are live
by Gabriel Cotelli Jan. 16, 2019

Jan. 16, 2019

Hi, We finished uploading all the videos of the conference. You can get the links and related info here <https://smalltalks2018.fast.org.ar/talks>. Regards, Gabriel in name of FAST

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[ANN] SETT (Store Export to Tonel Tools) for Pharo6.1
by Dale Henrichs Jan. 16, 2019

Jan. 16, 2019

GemTalkSystems is pleased to announce SETT (Store Export to Tonel Tools)[1]. SETT is open source project with an MIT license. SETT (Store Export to Tonel Tools) is a set of tools to export Smalltalk code from Store and write into the Tonel file format managed using Git. SETT is: * a Pharo 6.1 application, that * connects to a Postgres Database * containing source code history in VisualWorks Store format; and * writes to a Git repository * in Tonel format * maintaining all version history, source code and SCM metadata. SETT was developed last year to support one of our commercial customers in their conversion From Store to Rowan[2]. Rowan artifacts are produced as part of the output of SETT, but the Rowan artifacts can be ignored. The important bit is that SETT converts from Store to Tonel and maintains version history in git. Please see the project ReadMe[3] and Wiki[4] for additional details. Dale [1] https://github.com/GemTalk/SETT [2] https://github.com/GemTalk/Rowan [3] https://github.com/GemTalk/SETT#overview [4] https://github.com/GemTalk/SETT/wiki

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Re: [Pharo-users] Transforming objects
by Esteban Maringolo Jan. 16, 2019

Jan. 16, 2019

El miÃ©., 16 ene. 2019 a las 14:49, Ben Coman via Pharo-users (< pharo-users(a)lists.pharo.org>) escribiÃ³: > > > On Wed, 16 Jan 2019 at 17:16, LoÃ¯c PagÃ¨s <loic.pages(a)inra.fr> wrote: > >> >> Maybe a naive question ? >> > > Maybe #become: ... > https://gbracha.blogspot.com/2009/07/miracle-of-become.html > > Although miraculous, using #become: to model a business domain is harmful, and has more undesired side effects than benefits. So I would save it to a very limited use case scenarios, which are more related with low level stuff. Esteban A. Maringolo

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Re: [Pharo-users] adding instance variables (data) to the Object class
by Stephan Eggermont Jan. 16, 2019

Jan. 16, 2019

Petr Fischer via Pharo-users <pharo-users(a)lists.pharo.org> wrote: Hello! Weird question: why I can't add instance variables to the Object class (for example "oid" or something else)? Is it due to some internal (and different) VM "class layouts"? Or - can I inject my own information to all existing objects (any class)? You might want to take a look at the documentation of Magma. http://wiki.squeak.org/squeak/2665 Stephan

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