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

Re: [Pharo-users] NeoJSON Custom Mapping Question

by Sven Van Caekenberghe

Eric, > On 9 Jan 2019, at 00:34, Eric Gade <eric.gade(a)gmail.com> wrote: > > Hey guys, > > I'm toying with the idea of a Pharo implementation of ActivityStreams (https://www.w3.org/TR/activitystreams-core/#introduction) which is based on a subset of JSON called JSON-LD (for "linked data"). > > While I do not believe this would entail creating a whole JSON-LD implementation, I do have a question about how to implement reading/writing/mapping to and from the core set of object types in the specification. > > I am aware that giving any class #neoJsonMapping allows one to define the specifics of the mapping to and from objects of that class (I think this is super cool, by the way). The issue with ActivityStreams objects is that the "type" of object they represent is in the JSON itself as the property "type," for example: > > ``` > { > "@context": "https://www.w3.org/ns/activitystreams", > "name": "A simple note", > "type": "Note", > "id": "http://www.test.example/notes/1", > "content": "A simple note", > "replies": { > "type": "Collection", > "totalItems": 1, > "items": [ > { > "name": "A response to the note", > "type": "Note", > "content": "A response to the note", > "inReplyTo": "http://www.test.example/notes/1" > } > ] > } > } > ``` > > This refers to a top level ActivityStream object of type "Note" which we maybe want to parse into something like `ASNote`. > > My core question is this: how can we get a NeoJSONReader to determine which type of object to create by checking for a "type" property as soon as possible in the process? Because this property can show up in any order, we won't know what type of object to create until it is encountered. What is the best strategy there? > > Does the complexity suggest that we should simply parse incoming ActivityStream objects into the collection-and-dict default mapping and deal with creating the appropriate objects after that? In this case we could still use the custom mapping for the writing, which is not a problem since the "type" field will be associated with the class (ie, ASNote class >> #type will respond with 'Note' and we can go from there). > > Any thoughts or suggestions much appreciated! You describe the situation correctly: NeoJSON operates in 2 modes: (1) generating generic Arrays and Dictionaries (just like the spec) or (2) optionally mapping, stream based, directly, without intermediary representation, into domain instances (given a predefined static mapping) Using NeoJSONObject instead of Dictionary is just a convenience (it being a more JS like object). There is indeed another approach, using dynamic typing, that is not specifically supported in NeoJSON. As you remark yourself, that requires an intermediary representation, so one could just as well use option (1) and convert 'manually' in a second pass. That being said, it could/would be a nice addition to offer some support for this. Although there are multiple slightly different approaches. For example, there also is { "Point" : { "x" : 1, "y" : 2 } } Instead of { "_type" : "Point", "x" : 1, "y" : 2 } The key for the type/class can be different, the value can be anything, even 'com.java.graphics.Point'. Note also that typically, there are no collection types (and these would be way more complicated). Sven > -- > Eric

Jan. 9, 2019

Re: [Pharo-users] Documentation on Traits

by Steffen MÃ¤rcker

Maybe I missed that part: Can conflicts with slots occur? The section on conflicts only mentions methods as cause. Do you have a pointer to a slots documentation? Am 9. Januar 2019 20:32:51 MEZ schrieb "Cyril Ferlicot D." <cyril.ferlicot(a)gmail.com>: >Le 09/01/2019 Ã 18:49, Steffen MÃ¤rcker a Ã©critÂ : >> Nice. Do you know where to find details on stateful traits and slots? >I >> am familiar with stateless traits and wonder how state is >incoeporated >> and how conflicts are handled. >> > >The guide I send cover the user documentation of Stateful traits and >how >to handle conflict. > >What it does not cover are Slots (that are independents from Traits) >and >implementation documentation. > >> Best, Steffen >> > > >-- >Cyril Ferlicot >https://ferlicot.fr

Jan. 9, 2019

Re: [Pharo-users] Documentation on Traits

by Cyril Ferlicot D.

Le 09/01/2019 Ã 18:49, Steffen MÃ¤rcker a Ã©critÂ : > Nice. Do you know where to find details on stateful traits and slots? I > am familiar with stateless traits and wonder how state is incoeporated > and how conflicts are handled. > The guide I send cover the user documentation of Stateful traits and how to handle conflict. What it does not cover are Slots (that are independents from Traits) and implementation documentation. > Best, Steffen > -- Cyril Ferlicot https://ferlicot.fr

Jan. 9, 2019

[REMINDER] Camp Smalltalk 2019 in Charlotte, NC at the end of March!

by Mariano Martinez Peck

Happy New Year to All! For those that haven't heard, Instantiations is sponsoring a Camp Smalltalk on March 29th â March 31st 2019 in Charlotte, North Carolina. Please register for the event soon as spots will be limited. Event details and registration info are available at the following link: Camp Smalltalk Charlotte 2019 <https://www.eventbrite.com/e/camp-smalltalk-charlotte-2019-tickets-52380940…> Hope to see you there! -- Mariano https://twitter.com/MartinezPeck http://marianopeck.wordpress.com

Jan. 9, 2019

Re: [Pharo-users] Documentation on Traits

by Steffen MÃ¤rcker

Nice. Do you know where to find details on stateful traits and slots? I am familiar with stateless traits and wonder how state is incoeporated and how conflicts are handled. Best, Steffen Am 9. Januar 2019 15:21:09 MEZ schrieb Konrad Hinsen <konrad.hinsen(a)fastmail.net>: >Cyril Ferlicot <cyril.ferlicot(a)gmail.com> writes: > >> There is documentation on Traits here: >> >https://github.com/pharo-open-documentation/pharo-wiki/blob/master/General/… > >Great, thanks! > >Konrad.

Jan. 9, 2019

Re: [Pharo-users] NeoJSON Custom Mapping Question

by Esteban Maringolo

This could be very useful, in the past I used ExtJS which serialized its components in JSON format with a similar "xtype" attribute that was used to lookup the proper class to instantiate. But NeoJSON being stream based, and requiring a mapping to instantiate specific classes, the only, dirty, way I think about it is to instantiate everything as NeoJSONObject and then instantiate your desired object classes from the tree/graph of NeoJSONObjects. So basically you'd have to read the whole JSON stream and *then* instantiate your objects, this is more memory intensive than a stream based approach because you'll be instantiating intermediary objects, but it could work fine. Something like: ASNote fromJSON: (NeoJSONReader on: readStream) mapClass: NeoJSONObject; upToEnd Regards, Esteban A. Maringolo El mar., 8 ene. 2019 a las 20:35, Eric Gade (<eric.gade(a)gmail.com>) escribiÃ³: > Hey guys, > > I'm toying with the idea of a Pharo implementation of ActivityStreams ( > https://www.w3.org/TR/activitystreams-core/#introduction) which is based > on a subset of JSON called JSON-LD (for "linked data"). > > While I do not believe this would entail creating a whole JSON-LD > implementation, I do have a question about how to implement > reading/writing/mapping to and from the core set of object types in the > specification. > > I am aware that giving any class #neoJsonMapping allows one to define the > specifics of the mapping to and from objects of that class (I think this is > super cool, by the way). The issue with ActivityStreams objects is that the > "type" of object they represent is in the JSON itself as the property > "type," for example: > > ``` > { > "@context": "https://www.w3.org/ns/activitystreams", > "name": "A simple note", > "type": "Note", > "id": "http://www.test.example/notes/1", > "content": "A simple note", > "replies": { > "type": "Collection", > "totalItems": 1, > "items": [ > { > "name": "A response to the note", > "type": "Note", > "content": "A response to the note", > "inReplyTo": "http://www.test.example/notes/1" > } > ] > } > } > ``` > > This refers to a top level ActivityStream object of type "Note" which we > maybe want to parse into something like `ASNote`. > > My core question is this: how can we get a NeoJSONReader to determine > which type of object to create by checking for a "type" property as soon as > possible in the process? Because this property can show up in any order, we > won't know what type of object to create until it is encountered. What is > the best strategy there? > > Does the complexity suggest that we should simply parse incoming > ActivityStream objects into the collection-and-dict default mapping and > deal with creating the appropriate objects after that? In this case we > could still use the custom mapping for the writing, which is not a problem > since the "type" field will be associated with the class (ie, ASNote class > >> #type will respond with 'Note' and we can go from there). > > Any thoughts or suggestions much appreciated! > -- > Eric >

Jan. 9, 2019

Library to use multi-core in Pharo?

by Alexandre Bergel

Hi! Is there an effort to easily use multi-core or native processes in Pharo? I am thinking about a library that offer a construct like: future := Runner runInDifferentProcess: [ âThis block is run in a different OS processâ ] That would save the image under a different name, use OSSubProcess to launch a new Pharo with no UI. Is there a library available? Cheers, Alexandre -- _,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;: Alexandre Bergel http://www.bergel.eu ^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;.

Jan. 9, 2019

Re: [Pharo-users] Documentation on Traits

by Konrad Hinsen

Cyril Ferlicot <cyril.ferlicot(a)gmail.com> writes: > There is documentation on Traits here: > https://github.com/pharo-open-documentation/pharo-wiki/blob/master/General/… Great, thanks! Konrad.

Jan. 9, 2019

Re: [Pharo-users] Is it possible to follow an object through a computation?

by Marcus Denker

> On 3 Jan 2019, at 03:17, Esteban Maringolo <emaringolo(a)gmail.com> wrote: > > Hi Paul, > > You can set the object to be "read only" (aka "immutable") and handle the exception. > > E.g. > > | u | > u := User named: 'Paul'. > u beReadOnlyObject. > [ "your code modifying u's state" ] > on: ModificationForbidden > do: [ :ex | > ex halt. > "inspect state" > u beWritableObject. > ex resume > ]. > > Probably there is a better way to do this with slots, using default ones or subclassing `InstanceVariableSlot` for that instance only and halting on the `write:to:` method of it. > I started an experiment to turn the read Only mechanism into a general object change notifier: https://github.com/MarcusDenker/ChangeDetector This allows the following style of use: testObserveObjectWithModification [ | observed observer | observed := 'test2'. observer := self. observed notifyOnChange: observer. "the observed object is now read only" self assert: (observed isReadOnlyObject). "but we can change it!" observed at: 1 put: $T. self assert: observed equals: 'Test2'. "and the method #objectChangeNotified was called, setting flag" self assert: flag equals: #yes. observed stopNotifyOnChange: observer. self deny: (observed isReadOnlyObject). missing: -> we need to model read only for all tracked object (we need to remember the old state and restore it) -> think about threadsâ¦ is there a problem? Marcus

Jan. 9, 2019

Re: [Pharo-users] Documentation on Traits

by Cyril Ferlicot

On Wed, Jan 9, 2019 at 11:15 AM Konrad Hinsen <konrad.hinsen(a)fastmail.net> wrote: > > Dear Pharo experts, > Hello, > Is there any documentation on traits as implemented in Pharo 7? It's > easy to find discussions about the trait feature over the years, plus > slides and related stuff, but I am not sure what the current actually > implemented version is. I did manage to write and use a first trait > (https://github.com/khinsen/EqualityThroughVariablesTrait) but there > seem to be more advanced features such as slots that I don't know > anything about. There is documentation on Traits here: https://github.com/pharo-open-documentation/pharo-wiki/blob/master/General/… It might still needs review but it should help. It does not cover slots that is independent of Traits even if both can be used together. > > Cheers, > Konrad. > -- Cyril Ferlicot https://ferlicot.fr

Jan. 9, 2019