July 2016 - Pharo-users - lists.pharo.org

Re: [Pharo-users] Messages interceptions without using "halt"

by Steven Costiou

Hi Thierry, Esteban, i forgot to thnk you for your advices. I tried Metalinks but it cannot intercept messages receptions. I used Ghost, i have been able to do it with virus-proxies and it works well. Le 2016-04-26 15:07, Esteban Lorenzano a Ã©crit : > it is not what MetaLinks are for? > I think is easier than Ghost nowadays... but not sure :) > > look at > > ReflectivityControlTest>>testBeforeSend > > seems to be installing an interception "before send", who is what you are asking for. > > Esteban > > ps: but I might be wrong... Marcus can explain better :) > > On 26 Apr 2016, at 14:50, Thierry Goubier <thierry.goubier(a)gmail.com> wrote: > > Hi Steven, > > 2016-04-26 14:39 GMT+02:00 Steven Costiou <steven.costiou(a)kloum.io>: > > Hello, > > i am not new to Pharo nor to the list but this is the first time i speak here, so : hi =) > > I started a phd a few month ago (with Alain Plantec) on context oriented programming and dynamic programs adaptation. I am using Pharo for my experiments and i would like to intercept messages sent to an object just before they get to their receiver. To be more specific, when #msg is sent to an object o, i want to be able to intercept it just before it is actually executed with the following objects at my disposal : the receiver (o), the message or selector, the sender. My objective by doing that is to (try to) change the lookup for a given method, and to be able to choose in which class the lookup will start. > > I have been looking a bit and it does not seem to be a "simple" way to do that in Pharo. Is that even possible and if so, any advice on where i should look ? > The easiest would be to use proxy or ghost objects, which catches all message sends to a proxy of the real object and let you decide what to do with them. A recent announcement on Ghosts for Pharo 5 was done, maybe starting with that could be an idea. > > http://forum.world.st/Ann-New-version-of-Ghost-td4886357.html > > For old timers: wasn't Actalk done that way ? > > Thierry > > Thanks, > > Steven. -- kloum.io

July 24, 2016

Re: [Pharo-users] Changing method definition at runtime

by Steven Costiou

As i'm trying to build some kind of context oriented mechanism, i have the same need of behavior modification for a single instance of a class. I use virus-proxies in Ghost, that can intercept a message upon its reception in a particular object. From there it is possible to choose the code you want to run, being the original method or an other implementation. It works pretty well (by the way i still need to thanks the person here that recommended Ghost to me...). However you still need to store your behaviors implementations somewhere, in classes or blocks stored in variables... Le 2016-07-24 17:14, Eric Velten de Melo a Ã©crit : > Actually I wanted to have many different object instances with different behaviours picked at random from a list of available behaviours, but didn't find practical to create a class for each different method implementation and delegating to it, since there are many, possibly unlimited valid behaviours. > > So maybe changing method implementation at runtime is not what I want because the method implementation will be shared among all instances. What I had in mind was a functionality similar to prototyped languages like Self and Javascript in which you could change the behaviour inside the object and not the class/prototype. > > 2016-07-23 7:35 GMT-03:00 Norbert Hartl <norbert(a)hartl.name>: > >> Can you elaborate on the reason why want to modify behaviour? And how you would like it to happen? >> If the code you want to modify is your own code than you can solve that most of time with the things you already have. Your example using a block might be altered to be a strategy pattern. That means you keep one ore more instance variables for strategy objects. Then you delegate parts of your behaviour to those objects. You can based on context exchange those objects to adjust behaviour. >> If it is not feasible to change the internal state of an object but you know all possible variants you can implement all variations as methods in the object. The right method can be invoked by doing a double dispatch with another object providing contextual information. >> There are plenty of possibilities so you need to know what is the context that is responsible for switching behaviour and the requirements of the behaviour modifications. Can you alter the object? Is the number of modifications a fixed number? Does the modification need to be thread safe? >> >> Norbert >> >>> Am 23.07.2016 um 00:41 schrieb Eric Velten de Melo <ericvmelo(a)gmail.com>: >>> >>> Hello, >>> >>> One thing I try to do often is changing the behaviour of a method dynamically at runtime. The current way I do this is by having a block as an instance variable and having the method call this block, but I find this approach a bit cumbersome. Is there some other way or is this the recommended approach? >>> >>> I mean, I suppose methods could be changed dynamically by means of reflection somehow, but is this an easy or recommended way of programming in Smalltalk? Should slots make things easier? >>> >>> Eric -- kloum.io

July 24, 2016

Re: [Pharo-users] Changing method definition at runtime

by Eric Velten de Melo

Actually I wanted to have many different object instances with different behaviours picked at random from a list of available behaviours, but didn't find practical to create a class for each different method implementation and delegating to it, since there are many, possibly unlimited valid behaviours. So maybe changing method implementation at runtime is not what I want because the method implementation will be shared among all instances. What I had in mind was a functionality similar to prototyped languages like Self and Javascript in which you could change the behaviour inside the object and not the class/prototype. 2016-07-23 7:35 GMT-03:00 Norbert Hartl <norbert(a)hartl.name>: > Can you elaborate on the reason why want to modify behaviour? And how you > would like it to happen? > If the code you want to modify is your own code than you can solve that > most of time with the things you already have. Your example using a block > might be altered to be a strategy pattern. That means you keep one ore more > instance variables for strategy objects. Then you delegate parts of your > behaviour to those objects. You can based on context exchange those objects > to adjust behaviour. > If it is not feasible to change the internal state of an object but you > know all possible variants you can implement all variations as methods in > the object. The right method can be invoked by doing a double dispatch with > another object providing contextual information. > There are plenty of possibilities so you need to know what is the context > that is responsible for switching behaviour and the requirements of the > behaviour modifications. Can you alter the object? Is the number of > modifications a fixed number? Does the modification need to be thread safe? > > Norbert > > > Am 23.07.2016 um 00:41 schrieb Eric Velten de Melo <ericvmelo(a)gmail.com > >: > > > > Hello, > > > > One thing I try to do often is changing the behaviour of a method > dynamically at runtime. The current way I do this is by having a block as > an instance variable and having the method call this block, but I find this > approach a bit cumbersome. Is there some other way or is this the > recommended approach? > > > > I mean, I suppose methods could be changed dynamically by means of > reflection somehow, but is this an easy or recommended way of programming > in Smalltalk? Should slots make things easier? > > > > Eric > > >

July 24, 2016

Re: [Pharo-users] How learning Smalltalk can make you a better developer

by HernÃ¡n Morales Durand

Nice article! Cheers, HernÃ¡n 2016-07-24 9:35 GMT-03:00 horrido <horrido.hobbies(a)gmail.com>: > My article at TechBeacon has already become the third most popular (most > viewed) <http://techbeacon.com/?filter=popular> article at the website. > And its first week of publication isn't over yet! > > Apparently, this has become something of a "hot" topic. If you look at the > Live Listener Count > < > https://livefyre.zendesk.com/hc/en-us/articles/200329496-What-is-the-Live-L… > > > for my article, it's the highest of all the articles listed. Currently, it > stands around 50, but it started the week at around 120! All the other > articles on the list have a Live Listener Count of less than 25. > > In other words, I think interest in Smalltalk is particularly strong (if > somewhat latent). We just need to keep hammering the message home. > > > > -- > View this message in context: > http://forum.world.st/How-learning-Smalltalk-can-make-you-a-better-develope… > Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com. > >

July 24, 2016

Re: [Pharo-users] How learning Smalltalk can make you a better developer

by horrido

My article at TechBeacon has already become the third most popular (most viewed) <http://techbeacon.com/?filter=popular> article at the website. And its first week of publication isn't over yet! Apparently, this has become something of a "hot" topic. If you look at the Live Listener Count <https://livefyre.zendesk.com/hc/en-us/articles/200329496-What-is-the-Live-L…> for my article, it's the highest of all the articles listed. Currently, it stands around 50, but it started the week at around 120! All the other articles on the list have a Live Listener Count of less than 25. In other words, I think interest in Smalltalk is particularly strong (if somewhat latent). We just need to keep hammering the message home. -- View this message in context: http://forum.world.st/How-learning-Smalltalk-can-make-you-a-better-develope… Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.

July 24, 2016

Re: [Pharo-users] System Browser "Implementors of..." drill down?

by Alistair Grant

On Thu, Jul 21, 2016 at 07:03:40PM +0000, Henrik Nergaard wrote: > This can be achieved by selecting the message/class from the text area > and either right clicking and using the menu->submenu "Code search..." > or you can use the shortcuts: meta+m for implementors, meta+n for > senders, and meta+shift+n for references of it. There is also a > shortcut (meta+space) for selecting the whole text between separators > from where the cursor is. Personnally I find this inconvenient - a subjective choice, I know. On Fri, Jul 22, 2016 at 06:47:28AM +0000, Dimitris Chloupis wrote: > Learn to use GTSpotter , will make your experience 10 times easier and faster. This may be true, but I haven't figured it out yet. Until then... My vote would be to replace every instance of Implementers Of... / Senders Of... with a link to the MessageFlowBrowser. :-) Thanks, Alistair

July 23, 2016

Stack trying to use Pier 3 with Pharo 5

by Sean Glazier

Hi, After loading the configurations of Pier and checking for the lastest and loading them as well. I still get the following when I go to the peir setup off the seaside browse applications. WABidirectionalCache(Object)>>doesNotUnderstand: #associationsDo: PRAdminSetup class>>recursiveHandersOn:path:do: PRAdminSetup class>>recursiveDispatcherHandersDo: PRAdminKernelPathPair class>>kernelPathPairs PRAdminSetupChooseDistribution>>pierKernelNames PRAdminSetupChooseDistribution>>suggestKernelNameFrom: PRAdminSetupChooseDistribution>>kernelName MASelectorAccessor>>read: PRAdminSetupChooseDistribution(Object)>>readUsing: [ :each | result at: each put: (self model readUsing: each) ] in MACheckedMemento(MAMemento)>>pullRaw in Block: [ :each | result at: each put: (self model readUsi...etc... SortedCollection(OrderedCollection)>>do: MAPriorityContainer(MAContainer)>>do: MACheckedMemento(MAMemento)>>pullRaw MACheckedMemento(MAMemento)>>pull MACheckedMemento(MACachedMemento)>>reset MACheckedMemento>>reset MACheckedMemento class(MAMemento class)>>model:description: MAPriorityContainer(MAContainer)>>asComponentOn: PRAdminSetupChooseDistribution(Object)>>asComponent PRAdminSetupChooseDistribution>>selectDistributionComponent PRAdminSetupChooseDistribution>>children PRAdminSetupChooseDistribution(WAPresenter)>>childrenDo: WAVisiblePresenterGuide>>visitPresenter: WAVisiblePresenterGuide(WAPainterVisitor)>>visitComponent: PRAdminSetupChooseDistribution(WAComponent)>>accept: WAVisiblePresenterGuide>>visitDecoration: WAAnswerHandler(WADecoration)>>accept: WAVisiblePresenterGuide(WAPainterVisitor)>>visitDecorationsOfComponent: PRAdminSetupChooseDistribution(WAComponent)>>acceptDecorated: WAVisiblePresenterGuide(WAPresenterGuide)>>visit: Any help is appreciated :-) Kind Regards, Sean Glazier

July 23, 2016

Re: [Pharo-users] [ANN] JSONWebToken

by Sean Glazier

Hi, You can blame me for that because I could not find a JSON web token. It would be nice to have a search facility. Or am I missing an obvious feature I should be using? I am mostly experienced with cincom smalltalk. I like Pharo. My only criticism is that thing could be easier to set up. I am still trying to figure out how to get a commit to a git repository hosted of bit buck to commit etc. The customer set it there not me. I just have to get it to work ;-) Sean Kind Regards, Sean Glazier On Fri, Jul 22, 2016 at 5:45 PM, Norbert Hartl <norbert(a)hartl.name> wrote: > Hey Johan, > > didn't find it when starting my own. Mine is between 2 and 3 years old. > Maybe parallel development ;) > Mine is pretty basic and uses only SHA256. I implemented for internal use > and just released as sven was asking. > > Norbert > > Am 22.07.2016 um 19:20 schrieb Johan Brichau <johan(a)inceptive.be>: > > Hey Norbert, > > Also see here: http://smalltalkhub.com/#!/~JohanBrichau/Json-WebToken > > ;) > > Are you using cryptography package? > > Cheers, > Johan > > On 22 Jul 2016, at 10:17, Norbert Hartl <norbert(a)hartl.name> wrote: > > Hi, > > thanks to the inquiry of Sven I published an implementation of > JSONWebToken to smalltalkhub. It is available at > > http://smalltalkhub.com/#!/~NorbertHartl/JSONWebToken > > For those who don't know JSONWebToken or short JWT pronounced "jot" is a > token format suitable for authentication and authorization. The token > consist of a header, a payload and a signature. The header defines crypto > algorithms, compression and other things needed to read a token on > reception. The payload is called a claim set which is basically a > dictionary with well-known and custom keys. If we think about OAuth or > OpenId the values contained map directly to JWT claims. For OpenID connect > which is an identification mechanism on top of OAuth the usage of JWT is > one of the building blocks. > > What are the advantages in using JWT? > > - it defines a header for encoding the content so it is quite flexible in > the ways compression and encryption of the key is done > - defines a payload which maps arbitrary keys and there is a set of > well-known keys that implementations of OAuth, OpenID can understand > - defines a signature that makes it easy to trust the information > contained or to give the token to someone who is not trusted > - token format is a single line string so it can be used e.g. in HTTP > authentication headers > > A problem JWT can solve: > > In our company we have a lot of little REST servers serving some duties. > To minimize the chaos I want to have a central authentication and > authorization point. If we assume having 20 images running and we look at > typical way how authorization works: > > there is image A (Authentication), image S (Service) und client C. Client > C wants to use the service S > > 1. client C authenticates and retrieves authorization information from A > (or from S which redirects him to A) > 2. client C hands out the authorization information to S > 3. S needs to check at A if the information is valid (client C could have > modified it or generated it) > 4. S grants C access > > Taking the assumption of having 20 service images, every image would need > to get back to A in order to check authorization information. The more > services images you have the more load it will put on A. In a JWT use case > scenario the same would look like > > 1. client C authenticates and receives a JWT containing authorization > information. The token is signed by A > 2. client C hands out JWT to service S > 3. S checks the signature of A and knows that the authorization > information contained is valid. > 4. S grants C access > > FYI, > > Norbert > >

July 23, 2016

Re: [Pharo-users] Changing method definition at runtime

by Norbert Hartl

Can you elaborate on the reason why want to modify behaviour? And how you would like it to happen? If the code you want to modify is your own code than you can solve that most of time with the things you already have. Your example using a block might be altered to be a strategy pattern. That means you keep one ore more instance variables for strategy objects. Then you delegate parts of your behaviour to those objects. You can based on context exchange those objects to adjust behaviour. If it is not feasible to change the internal state of an object but you know all possible variants you can implement all variations as methods in the object. The right method can be invoked by doing a double dispatch with another object providing contextual information. There are plenty of possibilities so you need to know what is the context that is responsible for switching behaviour and the requirements of the behaviour modifications. Can you alter the object? Is the number of modifications a fixed number? Does the modification need to be thread safe? Norbert > Am 23.07.2016 um 00:41 schrieb Eric Velten de Melo <ericvmelo(a)gmail.com>: > > Hello, > > One thing I try to do often is changing the behaviour of a method dynamically at runtime. The current way I do this is by having a block as an instance variable and having the method call this block, but I find this approach a bit cumbersome. Is there some other way or is this the recommended approach? > > I mean, I suppose methods could be changed dynamically by means of reflection somehow, but is this an easy or recommended way of programming in Smalltalk? Should slots make things easier? > > Eric

July 23, 2016

Re: [Pharo-users] Changing method definition at runtime

by Thierry Goubier

Hi Steven, Eric, it can be done very easily by just recompiling the method, with optionally handling the fact that the underlying package may be marked as dirty. (i.e. have multiple method implementations, and switching between them by just calling #compile: on the class). Regards, Thierry Le 23/07/2016 Ã 11:20, Steven Costiou a Ã©crit : > Hello, > > a mean to achieve behavior modification of methods at runtime could be > context oriented programming (COP). It allows a method to have multiple > behavior variations that can be (de)activated dynamically. However to my > knowledge there is no context oriented extension for Pharo yet. > > I would also be interested by any known way to change method behavior > dynamically, as COP is not an option for now. Maybe by working on ast > nodes, by dynamically replacing them ? > > Steven. > > Le 2016-07-23 00:41, Eric Velten de Melo a Ã©crit : > >> Hello, >> >> One thing I try to do often is changing the behaviour of a method >> dynamically at runtime. The current way I do this is by having a block >> as an instance variable and having the method call this block, but I >> find this approach a bit cumbersome. Is there some other way or is >> this the recommended approach? >> >> I mean, I suppose methods could be changed dynamically by means of >> reflection somehow, but is this an easy or recommended way of >> programming in Smalltalk? Should slots make things easier? >> >> Eric > > > > -- > kloum.io

July 23, 2016