May 2014 - Pharo-users - lists.pharo.org

Downloading tweets

by Arturo Zambrano

Hi All, you can now download some code for downloading tweets using REST and Streaming Twitter APIs. It is far from complete but do the job we need for now. Besides tweets downloading you can also: - get users information. - retrieve the profile picture of users. - ask for the relationship of the two users Please find attached some info regarding dependencies (no metacello config for now), and manual login procedure for the first time you connect to twitter. We will work on tests, completion and more practical documentation soon. At the same time, when the visualization part of our Twitter thing is ready, we will communicate it. Thanks Rosario for her help, and Sven for advice on the streaming feature of Zinc. regards art

May 23, 2014

Re: [Pharo-users] Ghost Proxy

by Camille Teruel

On 22 mai 2014, at 22:29, Luc Fabresse <luc.fabresse(a)gmail.com> wrote: > > > > 2014-05-22 19:49 GMT+02:00 Camille Teruel <camille.teruel(a)gmail.com>: > > 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... > > I know the mechanism ;-) I know you know, but there is many people on this mailing list :). It was to stress that we need three indirections (1st lookup, 2nd lookup, forward request to handler) where 1 would be enough if done at the vm side. I call it a hack but it's not pejorative. It's the best we can do without vm modification after all. > but to me it is not hack it is a clever idea that let the programmer to decide what to do at the image side to implement crazy stuff without modifying the VM That sure is clever and it's great to not have to modify the vm, but modifying it to support proxies worth it in my opinion. > The VM is simple (one interception hook) while it enables to capture a lot of things. > Of course we can imagine something else at the VM side but the more code in the VM the less flexible it will be > > >> 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. > > we also explained that in the Ghost paper... > that is why cannotInterpret is better but yet incompelete to capture everything Only because of compilation optimizations. It is a real problem for certain applications. > > >> >> . 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. > > I have no clear idea yet on that so I must have look and you are certainly right > > Luc > >> >> 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

Re: [Pharo-users] Ghost Proxy

by Luc Fabresse

2014-05-22 19:49 GMT+02:00 Camille Teruel <camille.teruel(a)gmail.com>: > > 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... > I know the mechanism ;-) but to me it is not hack it is a clever idea that let the programmer to decide what to do at the image side to implement crazy stuff without modifying the VM The VM is simple (one interception hook) while it enables to capture a lot of things. Of course we can imagine something else at the VM side but the more code in the VM the less flexible it will be > > 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. > we also explained that in the Ghost paper... that is why cannotInterpret is better but yet incompelete to capture everything > > > >> . 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. > I have no clear idea yet on that so I must have look and you are certainly right Luc > > > 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

Re: [Pharo-users] Ghost Proxy

by Luc Fabresse

2014-05-22 20:37 GMT+02:00 Esteban A. Maringolo <emaringolo(a)gmail.com>: > 2014-05-22 13:06 GMT-03:00 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. > > 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. > > Funny thing is that Glorp proxies materialize the referenced object > when they receive #yourself > > > - 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. > > One thing is a Proxy that ALWAYS sits in between the real object and > its consumer forwarding messages or doing any other instrumentation, > and a different thing is a Stub which once materialized replaces all > references to the proxy with references to the new object > (#becomeForward:) and then vanishes (GCed). > > Having proxies in hashed collections can get very tricky if the hash > of the proxy/stub is different from the hash of the materialized > object. > yes exactly That is why in Ghost, you can choose what to intercept because it is application dependent Luc > > > Esteban A. Maringolo > >

May 22, 2014

Re: [Pharo-users] Pillar annotations for Latex

by Damien Cassou

Hi Ben, On Thu, May 22, 2014 at 6:09 PM, Ben Coman <btc(a)openinworld.com> wrote: > Now is there any important function missing, or is there a better way to do > this? thank you for your contribution. I would try to generate this instead: \begin{note} foo bar baz \end{note} This environment is meant for this. To output the \begin and \end parts, use canvas environment (look at the senders of #environment in the PRLaTeXWriter class for examples) To output the text, you can just write super visitAnnotatedParagraph: aParagraph > I also want add an annotation type, which I'll describe in a following post. I should we should think a bit how these should be handled. In the meantime, you can just hack around :-). And please add unit tests. -- Damien Cassou http://damiencassou.seasidehosting.st "Success is the ability to go from one failure to another without losing enthusiasm." Winston Churchill

May 22, 2014

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

by sergio_101

great! looking at STON next! thanks! On Thu, May 22, 2014 at 2:26 PM, ClÃ©ment Bera <bera.clement(a)gmail.com>wrote: > 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 >> > > -- ---- 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 Esteban A. Maringolo

2014-05-22 13:06 GMT-03:00 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. > 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. Funny thing is that Glorp proxies materialize the referenced object when they receive #yourself > - 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. One thing is a Proxy that ALWAYS sits in between the real object and its consumer forwarding messages or doing any other instrumentation, and a different thing is a Stub which once materialized replaces all references to the proxy with references to the new object (#becomeForward:) and then vanishes (GCed). Having proxies in hashed collections can get very tricky if the hash of the proxy/stub is different from the hash of the materialized object. Esteban A. Maringolo

May 22, 2014

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