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Re: [Pharo-users] Initializing a class with a Dictionary

by ClÃ©ment Bera

Hello, I think you should look at the STON framework. STON looks like JSON for smalltalk objects. Basically it does the same as your idea but instead of a dictionary it loads fields of an objects from a STON file which looks like a JSON file (a STON is kind of an extended Dictionary exported as a string, but it has support for more that instance variables). Now if you want to go your way, to me what you want to do looks fine. These methods can be used for development tools but also for frameworks and stuff like that. The thing to do it is to add this method in Object and add support so it can work on all objects in the system. Object>>#intializeWithDictionary: aDictionary self class isVariable ifTrue: ["specific case ?"] self class isBytes ifTrue: ["specific case ?"] self class isCompiledMethod ifTrue: ["specific case ?"] self class isSmallInteger ifTrue: ["specific case"] aDictionary keysAndValuesDo: [ :key :value | self instVarNamed: key put: value ifAbsent: [ self error: 'no ', key , ' found']. But as you can see there are many specific cases: CompiledMethod, bytes objects, word objects, immediate objects, variable-sized objects, weak objects and for Pharo 4 even others that you may need to handle in your code (Ephemerons, 2bytes and 4 bytes objects). If you don't get the specific cases (you may not know programming language internals), then imagine how you would make your code work to initialize an Array, a ByteArray or a CompiledMethod from a dictionary. Not easy, huh ? That's why I strongly recommend to use something like STON, because it is very easy to use, handle already all the specific cases, well documented (Sven always does fancy documentation) and it will be maintained in Pharo 4 for recent changes (because Sven likes to use the bleeding edge version of Pharo). Regards, Clement 2014-05-22 19:37 GMT+02:00 sergio_101 <sergio.rrd(a)gmail.com>: > > is it possible to initialize a class with a dictionary? my first thought > would be to create a method like: > > intializeWithDictionary: aDictionary > > then, loop through the elements and do something like: > > instVarNamed: key put: value > > but the book says: > > Caveat: Although these methods are useful for building development tools, > using them to develop conventional applications is a bad idea: these > reflective methods break the encapsulation boundary of your objects and can > there- fore make your code much harder to understand and maintain.-- > > should i avoid this? > > > ---- > peace, > sergio > photographer, journalist, visionary > #BitMessage BM-2D8VWUJSS41RFKh1ec83preVabHrnniExa > > http://www.Village-Buzz.com > http://www.ThoseOptimizeGuys.com > http://www.CodingForHire.com > http://www.coffee-black.com > http://www.painlessfrugality.com > http://www.twitter.com/sergio_101 > http://www.facebook.com/sergio101 >

May 22, 2014

Re: [Pharo-users] Calling an arbitrary method

by Guillermo Polito

Hi! On Thu, May 22, 2014 at 7:46 PM, sergio_101 <sergio.rrd(a)gmail.com> wrote: > In many cases, an object might have a method (filter, selector, etc) > attached to it so that the object can run the correct method.. > > for instance, an object might have a filterMethod variable with a value > 'filterByArtist'.. > > in ruby, i would do something like: > > instance.send(filter_method) > > how would i do that in pharo, > Selectors (method signatures) in Pharo are represented with Symbols, not Strings. In order to send a message from a given symbol you can do: object perform: #symbol or object perform: #symbol: with: anArgument or object perform: #symbol: withArguments: anArrayOfArguments for example 2 perform: #even. 2 perform: #+ with: 3 > and is this a bad idea? > It usually depends on what you want to achieve... You can also reach the same result having two filter objects: NullFilter>>filter: aCollection ^ aCollection ByArtistFilter>>filter: aCollection ^ aCollection select: [ :each | each artist = myArtist ] And you can even think about a third solution with blocks describing the filters. Making them objects to me gives you more power. They are objects, you can manipulate them, compose them, etc. Blocks can capture variables from the scope, but they are a bit obscure (as symbols are too). > > thanks! > > > -- > ---- > peace, > sergio > photographer, journalist, visionary > #BitMessage BM-2D8VWUJSS41RFKh1ec83preVabHrnniExa > > http://www.Village-Buzz.com > http://www.ThoseOptimizeGuys.com > http://www.CodingForHire.com > http://www.coffee-black.com > http://www.painlessfrugality.com > http://www.twitter.com/sergio_101 > http://www.facebook.com/sergio101 >

May 22, 2014

Re: [Pharo-users] Calling an arbitrary method

by Camille Teruel

On 22 mai 2014, at 19:46, sergio_101 <sergio.rrd(a)gmail.com> wrote: > In many cases, an object might have a method (filter, selector, etc) attached to it so that the object can run the correct method.. > > for instance, an object might have a filterMethod variable with a value 'filterByArtist'.. > > in ruby, i would do something like: > > instance.send(filter_method) > > how would i do that in pharo, and is this a bad idea? "instance perform: filterMethod asSymbol" If filterMethod is already a symbol you can omit asSymbol. It is slower than regular message send but it's also the safest reflective operation since it's the only one that doesn't break object encapsulation. > > thanks! > > > -- > ---- > peace, > sergio > photographer, journalist, visionary > #BitMessage BM-2D8VWUJSS41RFKh1ec83preVabHrnniExa > > http://www.Village-Buzz.com > http://www.ThoseOptimizeGuys.com > http://www.CodingForHire.com > http://www.coffee-black.com > http://www.painlessfrugality.com > http://www.twitter.com/sergio_101 > http://www.facebook.com/sergio101

May 22, 2014

Re: [Pharo-users] Ghost Proxy

by Camille Teruel

On 22 mai 2014, at 19:07, Luc Fabresse <luc.fabresse(a)gmail.com> wrote: > > > > > 2014-05-22 18:06 GMT+02:00 Camille Teruel <camille.teruel(a)gmail.com>: > > On 22 mai 2014, at 11:54, stepharo <stepharo(a)free.fr> wrote: > > > > >> In general, we should think about if is would make sense that the language comes with > >> a good proxy model by default. > > > > + 1 > > We should do that with Camille. > > Yes. > Now the problem is to agree on what is a "good model". > There is many use cases for proxies and they come with their own models and problems. > > yes sure > > Here are some requirements I can think of: > > - Uniformity: all objects can be wrapped, even special ones (it's a technicality but it's still important) > - Interception of all message: currently we cannot intercept #== and optimized control-flow messages like #ifTrue:ifFalse #to:do:, #whileTrue:, etc... > - Encapsulation (a.k.a the self problem): avoid leaking of references to the target. E.g. "aProxy yourself" should return the proxy not the target. > - Behavioral intercession: Not everything is a message send. What other events do we want to intercept? IV access is a must-have for me. > - Composition: Wrapping a proxy with another one should work as expected, i.e. applying both policies in order. > - Performances: intercepting message sends is slow, intercepting iv accesses is even worse (relying on code instrumentation). We would need VM support. > - Security: It shouldn't be possible to by-pass or corrupt a proxy policy. > - Delimited replacement: Ensure that a proxy is always used in place of its target throughout the processing of a message send, no matter the alias used (that is not necessarily "self"). Think about a read-only proxy for example. > > Right now, to intercept messages we have to rely on #cannotInterpret: hack > > why do you call it a hack? Because it's a hijack a safety check of the VM. We set the method dictionary of the proxy's class to nil (or of its superclass if the proxy must understand some messages). Since the VM doesn't know what to do with that, it calls #cannotInterpret: starting the lookup in the superclass of that class. This superclass then redefines #cannotInterpret: to hand over the message interception to the proxy's handler... > do you consider DNU as hack too? Using it to implement proxies? Yes. But in addition, DNU is bad since you can only intercept messages that are not understood. And you can also by-pass the message the proxy does understand by sending directly #doesNotUnderstand: to the proxy with a specific message as argument. > > . To intercept iv access or other events we have to rely on code instrumentation and delegation. > > yes but I would like to investigate if cannot achieve iv interception using special slots I doubt we can since it is the target's slots that are taken into account during compilation. Or else every slot in the system must be special => really poor performances. > > It would be easier if the VM would allow to create an object that controls its own interpretation (via a metaobject that defines a MOP for example). Such an object should at least be able to specify its message lookup and how to reads and writes IVs. > And optionally: > - how it sends messages > this one is possible with cannotInterpret > you intercept and then you decide what to do and maybe execute something else so you control message sending I was talking about interception of message sending (the message the target would have sent) not of interception of message reception (the living wage of any proxy implementation :) ). Like the others events, it also lies at the submethod level. > - how it resolves other variables (temporaries, arguments, globals, class variables) > - how it resolves literals > - how it executes primitives (because else the VM may cry) > - how it is assigned to a variable or passed in a message (to control static/dynamic aliasing respectively) > > all of those ones are submethod level and yes Ghost stops at the object granularity currently > > - ... many others ... > With such objects (+ operating by delegation instead of forwarding) we can solve most of the requirements listed above (well except performant delimited replacement). > All that to say that it is not easy... > > yes but it is interesting ;-) > and we also discuss "some parts" of that with Nick Great, let us know about the conclusions :) > > Luc > > >> (this way we would avoid that everyone creates one that is not completely working) > > > > > > >

May 22, 2014

Calling an arbitrary method

by sergio_101

In many cases, an object might have a method (filter, selector, etc) attached to it so that the object can run the correct method.. for instance, an object might have a filterMethod variable with a value 'filterByArtist'.. in ruby, i would do something like: instance.send(filter_method) how would i do that in pharo, and is this a bad idea? thanks! -- ---- peace, sergio photographer, journalist, visionary #BitMessage BM-2D8VWUJSS41RFKh1ec83preVabHrnniExa http://www.Village-Buzz.com http://www.ThoseOptimizeGuys.com http://www.CodingForHire.com http://www.coffee-black.com http://www.painlessfrugality.com http://www.twitter.com/sergio_101 http://www.facebook.com/sergio101

May 22, 2014

Initializing a class with a Dictionary

by sergio_101

is it possible to initialize a class with a dictionary? my first thought would be to create a method like: intializeWithDictionary: aDictionary then, loop through the elements and do something like: instVarNamed: key put: value but the book says: Caveat: Although these methods are useful for building development tools, using them to develop conventional applications is a bad idea: these reflective methods break the encapsulation boundary of your objects and can there- fore make your code much harder to understand and maintain.-- should i avoid this? ---- peace, sergio photographer, journalist, visionary #BitMessage BM-2D8VWUJSS41RFKh1ec83preVabHrnniExa http://www.Village-Buzz.com http://www.ThoseOptimizeGuys.com http://www.CodingForHire.com http://www.coffee-black.com http://www.painlessfrugality.com http://www.twitter.com/sergio_101 http://www.facebook.com/sergio101

May 22, 2014

Re: [Pharo-users] Ghost Proxy

by Luc Fabresse

2014-05-22 18:06 GMT+02:00 Camille Teruel <camille.teruel(a)gmail.com>: > > On 22 mai 2014, at 11:54, stepharo <stepharo(a)free.fr> wrote: > > > > >> In general, we should think about if is would make sense that the > language comes with > >> a good proxy model by default. > > > > + 1 > > We should do that with Camille. > > Yes. > Now the problem is to agree on what is a "good model". > There is many use cases for proxies and they come with their own models > and problems. > yes sure > Here are some requirements I can think of: > > - Uniformity: all objects can be wrapped, even special ones (it's a > technicality but it's still important) > - Interception of all message: currently we cannot intercept #== and > optimized control-flow messages like #ifTrue:ifFalse #to:do:, #whileTrue:, > etc... > - Encapsulation (a.k.a the self problem): avoid leaking of references to > the target. E.g. "aProxy yourself" should return the proxy not the target. > - Behavioral intercession: Not everything is a message send. What other > events do we want to intercept? IV access is a must-have for me. > - Composition: Wrapping a proxy with another one should work as expected, > i.e. applying both policies in order. > - Performances: intercepting message sends is slow, intercepting iv > accesses is even worse (relying on code instrumentation). We would need VM > support. > - Security: It shouldn't be possible to by-pass or corrupt a proxy policy. > - Delimited replacement: Ensure that a proxy is always used in place of > its target throughout the processing of a message send, no matter the alias > used (that is not necessarily "self"). Think about a read-only proxy for > example. > > Right now, to intercept messages we have to rely on #cannotInterpret: hack why do you call it a hack? do you consider DNU as hack too? > . To intercept iv access or other events we have to rely on code > instrumentation and delegation. > yes but I would like to investigate if cannot achieve iv interception using special slots > It would be easier if the VM would allow to create an object that controls > its own interpretation (via a metaobject that defines a MOP for example). > Such an object should at least be able to specify its message lookup and > how to reads and writes IVs. > And optionally: > - how it sends messages > this one is possible with cannotInterpret you intercept and then you decide what to do and maybe execute something else so you control message sending > - how it resolves other variables (temporaries, arguments, globals, class > variables) > - how it resolves literals > - how it executes primitives (because else the VM may cry) > - how it is assigned to a variable or passed in a message (to control > static/dynamic aliasing respectively) > all of those ones are submethod level and yes Ghost stops at the object granularity currently > - ... many others ... > With such objects (+ operating by delegation instead of forwarding) we can > solve most of the requirements listed above (well except performant > delimited replacement). > All that to say that it is not easy... > yes but it is interesting ;-) and we also discuss "some parts" of that with Nick Luc > > >> (this way we would avoid that everyone creates one that is not > completely working) > > > > > > >

May 22, 2014

Re: [Pharo-users] 3D with Pharo and OpenGL ?

by stepharo

Welcome Judith Do not hesitate to ask more questions. I may visit brest 1-5 to June. Guys we should really help judith because like that her boss can show how Pharo is cool to his own boss :) Judith you should look for a previous email of ronie (check the mailing-list archive)? I cannot browse it right now (preparing emails in the train). Stef On 22/5/14 17:11, RIOU Judith wrote: > > Hy, > > I'm working at Thales for a year internship and I would like to do > some OpenGL demos in smalltalk. I'm searching a demo which shows the > capacity to implement 3D drawing with Pharo. Does a demo already > available on Pharo 3.0 ? > > I aim to code my own demo and for example begin with a 3D drawing of > the earth (earth texture and arcball camera). > > Thanks. > > Judith > > [@@ THALES GROUP INTERNAL @@] >

May 22, 2014

Re: [Pharo-users] Versionner: Specifying un-configured packages as dependencies

by stepharo

+ 100 > The reason is that any package* should be self described. Your > configuration describes your project. If you use another piece of > software, it should also be self-described. > Let's take the following example: > > * for now, it's easy for you to add a direct dependency > to Roassal2Spec, just as if it was a part of your project ... => > no problem > * ... but it is not. Maybe tomorrow, Alex will need to add a > dependency to one or more packages for Roassal2Spec => you will > have problems because you will not get these dependencies. Of > course, you can still add them to your configuration but you can > easily see that you will end with a configuration including all > flatten dependencies, and with a lot of dependencies not directly > related to your project (transitive dependencies). Flatten > dependencies is really something that we should avoid, else > maintenance of dependencies will be a hell. > > That's why I'm really in favor of having configurations, even for one > single MC package inside the configuration. > > * I mean, not a Monticello package but a piece of software that you > want to deliver independently. It may be a whole project or part of > it. It may also refers to one or many Monticello packages

May 22, 2014

Re: [Pharo-users] 3D with Pharo and OpenGL ?

by kilon alios

you can find plenty of code in Roassal3d that I think uses the NBOpenGL library here http://www.smalltalkhub.com/#!/~ronsaldo/roassal3d NBOpenGL is basically a wrapper for OpenGL with Nativeboost. So if you are familiar with OpenGL , C and Nativeboost you are good to go using Roassal3d as an example to help you figure things out. I tried to make a set of tutorial but OpenGL proven very hard to tame. My main problem with my previous iMac was that Apple did not give error reporting for OpenGL which made it close to impossible to figure what went wrong with my OpenGL code. I have not tried to see if the situation improved with my new iMac that I purchased in the beginning of this year. Please note that previous iMac was 7 years old and still using Lion. Another tool that uses NBOpenGL is codecity. Bare in mind that OpenGL is pure graphics operation for the GPU so it does not provide with file loaders etc but I am sure using the tools I told you about you will fill in the gaps. On Thu, May 22, 2014 at 6:11 PM, RIOU Judith <judith.riou(a)fr.thalesgroup.com > wrote: > Hy, > > > > Iâm working at Thales for a year internship and I would like to do some > OpenGL demos in smalltalk. Iâm searching a demo which shows the capacity > to implement 3D drawing with Pharo. Does a demo already available on Pharo > 3.0 ? > > > > I aim to code my own demo and for example begin with a 3D drawing of the > earth (earth texture and arcball camera). > > > > Thanks. > > > > Judith > > [@@ THALES GROUP INTERNAL @@] > > >

May 22, 2014