June 2017 - Pharo-users - lists.pharo.org

Re: [Pharo-users] Wiring objects, IoC and Service Locator

by Ben Coman

On Tue, Jun 6, 2017 at 11:48 PM, Attila Magyar <m.magyar3(a)gmail.com> wrote: > I don't think using a DI container worth the effort. They add lots of > complexities and solve very little. For some reason DI containers became > very popular in the Java world, but if you take a look at other programming > communities you'll realize that many people are perfectly happy without > using these containers. Using DI and using a DI container is orthogonal. As > you also said you can just pass dependencies to objects to achieve loose > coupling. Yes, you have to do this manually but what's the big deal? We're > talking about code with cyclomatic complexity of 1. Calling a constructor > is > not a problem that need to be solved. Using an external XML configuration > to > describe object wiring is the worst idea ever. > > Here is an article about using plain old object composition to do DI > > http://blog.davidpeterson.co.uk/2011/01/object-oriented-example.html > > Some more thoughts about the problems associated with DI containers: > > http://www.natpryce.com/articles/000783.html I liked this... "the [Dependency Injection] pattern also used to be called "third-party binding" or "third-party connect": some third party is responsible for connecting an object satisfying the service requirements of a component" This makes the subject seem less esoteric. It reminds me of hearing that the first (secret) task when doing a PhD is to invent new terms for common ones, and base your writings on that. Perhaps its the same for consultants and framework developers. ;P Or maybe everything seems esoteric until you have experience with it and I've not done much with Java, certainly not big applications. Thx Peter for your example and how you prior experience compares to Pharo. cheers -ben > http://higherorderlogic.com/2011/07/is-dependency-injection-like-facebook > > > > -- > View this message in context: http://forum.world.st/Wiring-o > bjects-IoC-and-Service-Locator-tp4949280p4949720.html > Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com. > >

June 8, 2017

Re: [Pharo-users] Porting Transducers to Pharo

by Denis Kudriashov

2017-06-07 22:04 GMT+02:00 phil(a)highoctane.be <phil(a)highoctane.be>: > I read your note about DoubleAgents for the tests, well, yeah this one we > do not have. I read about it on the blog of its maker and it looked decent > indeed. > I think Mocketry can easily replace DoubleAgents but API is different and most tests will needed rewrites

June 7, 2017

Re: [Pharo-users] How to migrate an object to a subclass of its class but with new inst vars ?

by Denis Kudriashov

2017-06-07 22:30 GMT+02:00 Steven Costiou <steven.costiou(a)kloum.io>: > But would it not be faster to just change the class (which finally works > with a little tuning) ? In fact your solution with anonymous subclass is doing what I describe underhood.

June 7, 2017

Re: [Pharo-users] Wiring objects, IoC and Service Locator

by Peter Uhnak

> I don't see what is special about this. You can easily arrange instance > creation order with methods on the class-side of your domain classes. I will not use the term "class", but rather a "service" (service can be just a single class, but that is not always the case). The point of inversion of control is provide the class with what is needed instead of the class creating it on it's own. Sure, you can create class-side helper, however that is very limited, such as the examples/samples as you've demonstrated. To give you an example, imagine that you have a class PeopleService that manages database of people, so it needs a connection to the database. Implemented in a naive way the class would have hard-coded credentials to a MySQL database and it would execute raw SQL queries. This works for a single class, but it creates a mess and mingles concerns; so instead you inverse the control and you provide PeopleService with e.g. a Persistence instance, which is already connected to the database; note however that you cannot just create the Persistence on the class-side, because you wouldn't even know what to instantiate (as you could e.g. use DbPersistence, FilePersistence, ...). And this is just a basic example. Imagine that the PeopleService also needs other services for it's use, and those services need more services, and you want to keep everything separated as much as possible... instantiation by hand will simply not cut it So the service locator/DI configuration (whether as annotations or in a XML file) keeps the actual classes separated from concrete instances; the service depends on abstract interfaces, not specific classes; only the conf determines the specific ones, and more often than not there will be several different configurations _at the same time_. To continue with the example you could have one config production using e.g. OraclePersistence, another for development using MySQLPersistance, another for test server using MemoryPersistence, etc. (also with different credentials, and whatnot). Keep in mind however that relates primarily to using application frameworks, where the framework mandates the control, and the framework is the one calling you, and therefore it will also provide you with necessary parts. After all you are not even creating PeopleService class, the framework instantiates it for you and gives it to another services/classes that needed it. Now I don't feel like there are many application frameworks in Pharo, maybe Seaside has something of this sorts? I guess Spec can be a bit framework-y, as the basic spec widgets do not actually know what Morphic counterparts will be created for them, and Spec looks up the actual class in a hard-coded data table (which might as well be a XML file), but that comes closer to ServiceLocator than DI (as Spec widgets should not actually communicate down to morphic). I've used dependency injection for five years at my previous work and frankly I cannot imagine living without it there, but I've never felt the need for it in Pharo. This is probably more related to working in Pharo on completely different things and writing small libraries. However I wouldn't be surprised if the liveness of Smalltalk/Pharo environment eliminated some of the problems that DI is trying to solve. But then again, there are many ways to build systems, and not all need or benefit DI/IoC. Peter > Indeed, the GTTools are set up to work with in-Image sample data. Look at > implementors of #sample and #example. > There was quite some bike-shedding over the naming convention (and I forget > the final result), but hopefully it provide the general idea... > > http://forum.world.st/a-request-to-change-the-meaning-of-lt-example-gt-prag… > http://forum.world.st/lt-example-gt-lt-examplar-gt-td4911728i20.html > http://forum.world.st/Existing-lt-script-gt-lt-example-gt-pragmas-and-new-G… > > > > > > > I started, however, to question DI as a valid mechanisms because of it's > > complexities and other problems. The article from Fowler provides the > > service locator as an alternative which seems to me much simpler and > > completely fine solution for the problem. > > > > If it seems suitable, then to quote Nike, just do it ;) > > > > > So, to answer you question "Is it any more complicated than that?": In > > the DI approach, yes it can be, but I don't think so in the service locator > > approach. > > > > I am asking here because I wanted to know how people from Smalltalk deal > > with this problem. As it seems there is no standard approach, nor this is > > perceived as a problem... > > > > > DI or Service Locator are both "implementations" of your need. Can we take > step backward to see what is your need? To kick off, I hazard a guess at > some possible needs... > > 1. To switch between configurations to use production data and test data ? > 2. To make this switch during CI testing and production deployment ? > 3. To switch from the command line ? > 4. Want the configuration to editable remotely? e.g. from a text editor? > ? > ... > > > > > You think it is enough to do the wiring by hand? > > > > I'm having trouble understanding this "by hand" concept. > Don't you create the xml configuration file by hand? > You can just as easily > > > > > It is ok to use a service locator approach? Or wouldn't you care about > > that? > > > > If it works, its okay. > > So very generally, I'd avoid starting with any external test data, so as to > not distract myself by that implementation. > I'd copy-paste some test data into the class-side-methods of the domain > classes and hack some instance creation code around them. > Build your first tests around those. Then later, consolidate them via an > InImageTestData object that you'll later replace with ExternalTestData > > > > > > > > > but I'll add, it was so much simpler to understand without all that Java > >> typing boiler plate. > > > > > > Yeah, that's for sure! I am just used to read Java code. > > > > []s, > > Vitor > > > > > > > As an aside, try evaluting "Smalltalk tools inspect" > and debugging "Smalltalk tools browser open" > > cheers -ben

June 7, 2017

Re: [Pharo-users] How to migrate an object to a subclass of its class but with new inst vars ?

by Steven Costiou

Hmm ok, but can i easily make b become a again later ? I guess i would just need to instanciate a new a... But would it not be faster to just change the class (which finally works with a little tuning) ? I can't test right now but i will compare the two things... Le 2017-06-07 21:59, Denis Kudriashov a Ã©crit : > 2017-06-07 16:43 GMT+02:00 Steven Costiou <steven.costiou(a)kloum.io>: > >> Yes but when you do that you loose all the states from "a" (at least the values). You have to do state migration management... > > You just need extra step to copy all state from old object: > >> b := B new. > >> b copyFrom: a. > >> a becomeForward: b.

June 7, 2017

Re: [Pharo-users] Porting Transducers to Pharo

by phil＠highoctane.be

Hi Steffen, I have created a repo on Github with the code and added you as an admin on it as well. https://github.com/Pharophile/Transducers I've put a README. md with your notes, and under packages/ you'll find 3 packages: Transducers-Core Transducers-Examples Transducers-Tests Tests is empty and Examples has the example from the mailing list. I ran the Renraku quality assistant tool and there are a few issues in the package. I did all of this in a Pharo 6 image using Iceberg. [image: Inline image 1] I guess that you can clone the repo using the Origin you see in the screenshot. I used https out of lazyness because I didn't wanted to deal with ssh keys etc. Tell me how it goes for you. I read your note about DoubleAgents for the tests, well, yeah this one we do not have. I read about it on the blog of its maker and it looked decent indeed. For the critics browser, it goes like this: [image: Inline image 2] Then look at the warnings. A bunch of them are non issues but there are Undeclared things in need of a fix (e.g. IndexNotFoundError) Best, Phil On Wed, Jun 7, 2017 at 11:29 AM, Steffen MÃ¤rcker <merkste(a)web.de> wrote: > Hi Phil, > > that's great. I do have a GitHub account (merkste) but none at > SmalltalkHub. Is there a recommendable doc on how to use Git from Pharo? > > Best, Steffen > > > > Am .06.2017, 14:09 Uhr, schrieb phil(a)highoctane.be <phil(a)highoctane.be>: > > Hi Steffen, >> >> I am willing to help you create the package in SmalltalkHub or Github >> based >> on your files/changeset. >> >> Do you have a github and/or SmalltalkHub account? >> >> Best, >> Phil >> >> >> On Tue, Jun 6, 2017 at 1:08 PM, Steffen MÃ¤rcker <merkste(a)web.de> wrote: >> >> Hi! >>> >>> If the need arises, we could of course factor the compact notation out >>> into >>> >>>> a separate package. >>>>> >>>>> Good idea >>>> [...] I do not want to help promoting a syntax that alienates me (and >>>> others because other people reported the saem to me). >>>> >>>> >>> I understand. Btw, I'd really, really appreciate if others post their >>> thoughts and feedback here as well. Discussion helps moving things >>> forward. >>> =) >>> >>> >>> (collection transduce map: #squared) take: 1000. >>> >>>> >>>>> >>>> To me this is much more readable. >>>> >>>> >>> Well, I'll provide that extension once it is finished. >>> >>> I cannot and do not want to use the other forms. >>> >>>> >>>> >>> >>> collection transduce >>> >>>> map: #squared; >>>>> take: 1000. >>>>> >>>>> But as the message chain has to modify the underlying object >>>>> (an eduction), very snaky side effects my occur. E.g., consider >>>>> >>>>> eduction := collection transduce. >>>>> squared := eduction map: #squared. >>>>> take := squared take: 1000. >>>>> >>>>> Now, all three variables hold onto the same object, which first squares >>>>> all elements and than takes the first 1000. >>>>> >>>>> >>>> This is because the programmer did not understand what he did. No? >>>> >>>> >>> Sure. ;-) Nevertheless, it would be very hard to debug. All of which are >>> the reasons I wouldn't implement that variant. ;-) >>> >>> >>> PS: I played with infinite stream and iteration back in 1993 in CLOS. >>> >>>> Now I do not like to mix things because it breaks my flow of thinking. >>>> >>>> >>> >>> I am not sure whether I understand what your mean by mixing. Concerning >>> transducers, the ability to handle infinite sources in only a (natural) >>> side-effect of the ability to finish reductions before all elements are >>> processed, e.g., like #detect: and such. >>> >>> Best, Steffen >>> >>> >>> >>> >>> >>> > >

June 7, 2017

Re: [Pharo-users] How to migrate an object to a subclass of its class but with new inst vars ?

by Denis Kudriashov

2017-06-07 16:43 GMT+02:00 Steven Costiou <steven.costiou(a)kloum.io>: > Yes but when you do that you loose all the states from "a" (at least the > values). You have to do state migration management... You just need extra step to copy all state from old object: b := B new. b copyFrom: a. a becomeForward: b.

June 7, 2017

Re: [Pharo-users] is it related to Freetype or Athens?

by Peter Uhnak

On Tue, Jun 06, 2017 at 07:33:04PM +0200, Hilaire wrote: > Hi there, > > A Dr. Geo user on Ubuntu 64bits 16.04 got that buggy rendering of the > canvas, then on some situation the rendering completely stop on a red > screen, with a stack showing may be a zero divide error. I did not get > access to the PharoDebog yet. > > Fonts on the screenshot is not right too. Could it be a mixed problem > between FreeType and Cairo? Any first though on the issue welcome. There were couple GC/memory related issues in the VM's plugin, that were fixed or worked around in the Pharo 6 VM that apparently were present for a long time... so maybe that's also part of what you've experienced...

June 7, 2017

MD5 is broken (Cryptography)

by casimiro barreto

MD5 (non primitive and with primitive) is broken because it relies on the conversion of Character to SmallInteger so the method shiftBits: Problem happens at ThirthyTwoBitRegister>>reverseLoadFrom:at: which is called from MD5NonPrimitive>>proccessBuffer: Error is: Instance of Character did not understand #bitShift and happened at: reverseLoadFrom: aByteArray at: index "Load my 32-bit value from the four bytes of the given ByteArray starting at the given index. Consider the first byte to contain the most significant bits of the word (i.e., use big-endian byte ordering)." hi := ((aByteArray at: index + 3) bitShift: 8) + ( aByteArray at: index + 2). low := ((aByteArray at: index + 1) bitShift: 8) + ( aByteArray at: index). -- The information contained in this message is confidential and intended to the recipients specified in the headers. If you received this message by error, notify the sender immediately. The unauthorized use, disclosure, copy or alteration of this message are strictly forbidden and subjected to civil and criminal sanctions.

June 7, 2017

Re: [Pharo-users] RewriteToolbuilder question

by werner kassens

On 06/07/2017 08:11 PM, Mark Rizun wrote: > At first, I was not able to reproduce the error, but then I realised > that you probably don't save the content of lower left and right parts > (`@.Statements).Use cmd+s to save changes. > The error is raised because parser tries to parse the old code (same > as in upper left part) with a method intended for rewrite rules. > That should fix it. > If you have any other questions related to RewriteTool don't hesitate > to ask. Thank you, Mark. werner

June 7, 2017