[Pharo-users] Questions about NewValueHolder and Model

[dorellang]

Hi everyone!

I was trying to find out how to propagate changes through widgets in the
Spec UI framework, and so far it seems to me that using NewValueHolder
objects is the most proper way right now. Am I wrong?

However I have some questions regarding this class:

(BTW I am using a Pharo 7 image)

First, you may notice that NewValueHolder extends the Model class, whose
class comment simply says "Provides optimized model support". The first
thing I thought coming from a non-Smalltalk background was like "What is
that supposed to mean?". Then I tried to make sense of it, but you know,
this has been hard because Model has a lot of methods that aren't too
related IMHO. For instance let's take all the methods under the 'stepping'
and 'stepping-window' protocols ...what are they intended to do? After doing
some research I think they are some kind of mechanism from the Morphic
framework to setup actions that will be performed periodically, probably for
supporting animations or something, but what does this have to do with being
a Model anyway?

All of this has been pretty confusing, but I think I've understood it better
after reading this post about Smalltalk MVC:
http://peter.michaux.ca/articles/smalltalk-mvc-translated-to-javascript . I
know this may be a bit obvious for veteran Smalltalkers, but now it has
become clearer to me that this Model class is the M of the MVC framework
that was used in ye olden days to build Smalltalk UIs. Which is weird
because as far as I know MVC doesn't exist in Pharo. So I asked myself:
"Shouldn't this be killed? Why is it kept? (at least it should be cleaned up
I think)". And after searching the references and senders of the methods I
think it mostly comes down to Morphs. Is it feasible to clean this up? I
think all of this should be explicitely documented at least, you know, all
this Model API. Currently it's too implicit, not friendly for newcomers and
too mixed up with random Morphic stuff (which should be dying soon anyway).

Some other thing that bothers me it's that that most of the methods in Model
are defined in Object too. I understand that that was made in the original
MVC to have the ability to use anything as a Model, but I don't think that's
necessarily the best option. It would be cleaner perhaps to have an asModel
message which creates a ProxyModel object which implements all the Model API
methods and then proxies the rest to the underlying instance; or maybe a
more pragmatic approach would be like moving all these Model methods in
object to an extension protocol; or ...hey, it's 2018! Today we have traits, 
we could create a Trait with all those methods and then just let the current
Model class use it.

That's are my thoughts about the Model class. Now I'm not an expert, so they
should be taken with a grain of salt ;)

Coming back to the NewValueHolder, other two issues came to my mind:

- What's the deal with the old ValueHolder class? Apparently it's not used
anywhere. I think it should be removed, and NewValueHolder should be renamed
to ValueHolder.

- Some messages of NewValueHolder are also in the Model class in the
'announcing' protocol... What's the point of this polymorphism? This is not
like the classical Model API at all, which uses the dependents and updating
protocols. All these methods under the 'announcing' protocol use a totally
unrelated way of propagating changes. This breaks SRP, shouldn't we have
instead like a NewModel class which uses this new Announcement-based
mechanism for propagating changes and don't conflate the two things?

- In the same fashion, I don't think there isn't any good reason for having
the NewValueHolder as a Model subclass; at least the Model that implements
the behavior from the old MVC framework. For the record in my image I've
done 'Object subclass: #NewValueHolder (...)', copied all the announcing
methods to NewValueHolder and added an announcer instance variable and it's
going fine so far, but that might be because all Objects can be used as
models in the MVC sense. Anyway, after some use 'Object classVariableNamed:
#DependentsFields' still prints "#DependentsFields->a
WeakIdentityKeyDictionary()" :P

I think that's it, or maybe I forgot something I don't know haha



--
Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

Re: [Pharo-users] Questions

[Sven Van Caekenberghe]

And there is this chapter in the new book:

https://ci.inria.fr/pharo-contribution/job/EnterprisePharoBook/lastSuccessfulBuild/artifact/book-result/NeoCSV/NeoCSV.html

But I understood that Alejandro has to write a simple CSV parser from first 
principles himself.

> On 28 Jul 2016, at 09:51, Julien Delplanque  wrote:
> 
> Hello,
> 
> Have a look at "NeoCSV" project from the catalog browser.
> 
> This document [1] may help you as well. There is a dedicated section for 
> NeoCSV.
> 
> Regards,
> Julien
> 
> Links:
> [1]: 
> http://www.slideshare.net/philippeback/pharo-days-2016-data-formats-and-protocols
> 
> 
> On 28/07/16 08:30, Alejandro Adgi Romano wrote:
>> Hello, my name is Alejandro.
>> 
>> I´m writting code in Pharo 5.0.
>> 
>> I need finish an exercise of my career.
>> 
>> My question is:
>> 
>> ¿Could you tell me how can read and write a CSV File?
>> 
>> I need the code, because i don´t understand how is the use of NeoCSV or
>> another tool for this.
>> 
>> In the exercise, the text says:
>> "You must Show the CashFlow por One Period with information from
>> CashFlow.csv"
>> 
>> 
>> ¿How can I do this?
>> 
>> Thanks!!!
>> 
> 
> 

Re: [Pharo-users] Questions

[Julien Delplanque]

Hello,

Have a look at "NeoCSV" project from the catalog browser.

This document [1] may help you as well. There is a dedicated section for 
NeoCSV.


Regards,
Julien

Links:
[1]: 
http://www.slideshare.net/philippeback/pharo-days-2016-data-formats-and-protocols



On 28/07/16 08:30, Alejandro Adgi Romano wrote:

Hello, my name is Alejandro.

I´m writting code in Pharo 5.0.

I need finish an exercise of my career.

My question is:

¿Could you tell me how can read and write a CSV File?

I need the code, because i don´t understand how is the use of NeoCSV or
another tool for this.

In the exercise, the text says:
"You must Show the CashFlow por One Period with information from
CashFlow.csv"


¿How can I do this?

Thanks!!!

[Pharo-users] Questions

[Alejandro Adgi Romano]

Hello, my name is Alejandro.

I´m writting code in Pharo 5.0.

I need finish an exercise of my career.

My question is:

¿Could you tell me how can read and write a CSV File?

I need the code, because i don´t understand how is the use of NeoCSV or
another tool for this.

In the exercise, the text says:
"You must Show the CashFlow por One Period with information from
CashFlow.csv"


¿How can I do this?

Thanks!!!

Re: [Pharo-users] Questions about MetaLink

[Marcus Denker]

 
 For instance, in order to address a layer with no MetaObjects execution, a
 layer with MetaObjects for logging or breakpoints, an other layer with
 custom MetaObjects, etc.
 I don't see how it would be possible to limit the scope of the active layers
 configuration, just for a block evaluation for exemple... From RFMetaContext
 maybe, but how ?…
 
 One thing I want to add is to make the condition (optionally) into an object
 and then allow reflectivitly to turn on/of links without having to actually 
 change
 the #condition: itself.
 

This is now in Pharo5… links can be turned on/off reflectively by using
#enable and #disable. 
I works by wrapping the original condition into a RFCondition object. 

#disable puts just “false” as the outer condition, but one could put there
more complex conditions, too

Marcus

Re: [Pharo-users] Questions about MetaLink

[Marcus Denker]

 On 29 Apr 2015, at 22:59, Glenn Cavarlé gl...@cavarle.fr wrote:
 
 Hi,
 
 I'm playing with Slots and MethodWrappers to customize instVar
 reading/writing and method calls.
 In my experiments, Slots and MethodWrappers hold meta-description objects
 used at runtime to apply some filters, validations and to compose or
 delegate methods behavior.
 
Interesting!

 I'm really interested in the progress of MetaLink, I saw that it will be
 possible to use hooks like #instead or #arround.
 Are these hooks can replace the use of MethodWappers ?

Yes!

 Will it be possible to call a MetaObject's method instead of a method's body
 and with the passed arguments ?
 
Yes, this will work very soon… in a simple version (only one replace link 
allowed).
(Later this will be generalized AOP style as an #around with the possibility to 
“proceed”
to the replaced node).

What I am porting now from the prototypes is the functionality to hand arguments
over to meta objects.

before links on methods are already working:

link := MetaLink new
metaObject: [ self halt ].

(ReflectivityExamples#exampleMethod) ast link: link.

execute it:

ReflectivityExamples new exampleMethod.

(ReflectivityExamples#exampleMethod) symbolic 

'21 20 pushConstant: [ self halt ]
22 C9 send: value
23 77 pushConstant: 2
24 21 pushConstant: 3
25 B0 send: +
26 7C returnTop’

(This example, too, shows that a block can be a meta object, this means that 
this
can be used as a very easy to use instrumentation framework, too, without the 
need
to create explicit classes and methods for meta objects).

 The announcement of meta-levels gives me ideas, would not it be interesting
 to have something like meta-layers?

Yes!

 For instance, in order to address a layer with no MetaObjects execution, a
 layer with MetaObjects for logging or breakpoints, an other layer with
 custom MetaObjects, etc.
 I don't see how it would be possible to limit the scope of the active layers
 configuration, just for a block evaluation for exemple... From RFMetaContext
 maybe, but how ?…

One thing I want to add is to make the condition (optionally) into an object
and then allow reflectivitly to turn on/of links without having to actually 
change
the #condition: itself.

Then links themselves could target these control meta objects…

It is definitly interesting. E.g. one might want to have break points active, 
yet run the tests with them disabled.

Marcus

[Pharo-users] Questions about MetaLink

[Glenn Cavarlé]

Hi,

I'm playing with Slots and MethodWrappers to customize instVar
reading/writing and method calls.
In my experiments, Slots and MethodWrappers hold meta-description objects
used at runtime to apply some filters, validations and to compose or
delegate methods behavior.

I'm really interested in the progress of MetaLink, I saw that it will be
possible to use hooks like #instead or #arround.
Are these hooks can replace the use of MethodWappers ?
Will it be possible to call a MetaObject's method instead of a method's body
and with the passed arguments ?

The announcement of meta-levels gives me ideas, would not it be interesting
to have something like meta-layers?
For instance, in order to address a layer with no MetaObjects execution, a
layer with MetaObjects for logging or breakpoints, an other layer with
custom MetaObjects, etc.
I don't see how it would be possible to limit the scope of the active layers
configuration, just for a block evaluation for exemple... From RFMetaContext
maybe, but how ?...
It is just an idea on the fly, Maybe it's already possible to do something
like that or it would be just useless in practice.

Thanks a lot Marcus for your work on Slot and MetaLink.

Best regards,
Glenn.



-
Glenn Cavarlé
--
View this message in context: 
http://forum.world.st/Questions-about-MetaLink-tp4823035.html
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Re: [Pharo-users] Questions about Magma

[Thushar G R]

Hi ,


@Stéphane Ducasse
I will definitely give mango DB a try. I was using GLORP since a very long
time (not in pharo) so when i looked at magma i got interested. So all
other options stayed  back for later in my list.

@Stuart Herring
The changes as far as i know is related to SystemAnnouncer , FileReference
and the vm parameterAt: . So what i plan to do is to load all the latest
stuff a
from ss3.gemstone.com/ss/MaBase Ma-Client-Server Magama , make the changes
and run the tests , with *MagmaTestCase fullSuite maDebug*

Hopefully i may get some bugs which i can fix...else i will be contacting
the author. I hope Chriss muller will be reading this...and correcting me
if i wrote something wrong.

Thanks to all.

Thushar



thuchu


On Wed, Jun 5, 2013 at 5:30 AM, Stuart Herring
st-li...@stuartherring.comwrote:

 Hi Thushar,

 Magma's developer mostly uses Squeak, so the latest version of Pharo
 that Magma works more or less out-of-the-box on is 1.3.
 I made a start on porting it to 1.4, and then 2.0 but then promptly
 ran out of time.  However, as far as I'm aware the porting should
 mostly consist of the change to SystemAnnouncer, and Filesystem as you
 mentioned.
 Magma has a pretty comprehensive test suite, so it should be
 relatively easy to verify any porting effort.

 I know that people seem to be gravitating towards other solutions, as
 Stéphane mentioned, but Magma is still an excellent tool, and is
 ridiculously simple to use.  I like it enough that for my own
 projects, I'm still using Pharo 1.3 so I can use it, until the desire
 to use 2.0 and beyond finally pushes me into completing my porting
 effort ;)

 If you do want to give the porting a go yourself, I'd suggest posting
 to the Magma list.  Chris is very supportive of porting efforts.

 Regards,
 Stuart

 On 4 June 2013 22:32, Thushar G R thushar...@gmail.com wrote:
  Hi all,
 
 
  I am new here in this list. I have already asked this question in stack
  overflow, but not much luck. So i thought ill contact the gurus directly.
 
  I am considering Magma to be used for one of my projects , which is
 nothing
  but a custom game center to connect my game and store user details and
  retrieve it. This would be the first time that i will be using pharo for
 one
  of my projects ( in fact this is the first time that i am able to decide
 for
  my self - the client has not preferences in terms of technology
 selection).
 
  So my concern is this, is Magama upgraded to be used in Pharo 2.0? What
 if i
  load it  and change the SystemChangeNotifiers with SystemAnnouncer and
 so on
  , will it cause any trouble in the future. I Appreciate any comments for
  this.
 
 
  Regards
 
  thushar

[Pharo-users] Questions about Magma

[Thushar G R]

Hi all,


I am new here in this list. I have already asked this question in stack
overflow, but not much luck. So i thought ill contact the gurus directly.

I am considering Magma to be used for one of my projects , which is nothing
but a custom game center to connect my game and store user details and
retrieve it. This would be the first time that i will be using pharo for
one of my projects ( in fact this is the first time that i am able to
decide for my self - the client has not preferences in terms of technology
selection).

So my concern is this, is Magama upgraded to be used in Pharo 2.0? What if
i load it  and change the SystemChangeNotifiers with SystemAnnouncer and so
on , will it cause any trouble in the future. I Appreciate any comments for
this.


Regards

thushar

Re: [Pharo-users] Questions about Magma

[Stéphane Ducasse]

Excellent.
We would really like to have magma running on Pharo. Please push

Stef

 Hi Thushar,
 
 Magma's developer mostly uses Squeak, so the latest version of Pharo
 that Magma works more or less out-of-the-box on is 1.3.
 I made a start on porting it to 1.4, and then 2.0 but then promptly
 ran out of time.  However, as far as I'm aware the porting should
 mostly consist of the change to SystemAnnouncer, and Filesystem as you
 mentioned.
 Magma has a pretty comprehensive test suite, so it should be
 relatively easy to verify any porting effort.
 
 I know that people seem to be gravitating towards other solutions, as
 Stéphane mentioned, but Magma is still an excellent tool, and is
 ridiculously simple to use.  I like it enough that for my own
 projects, I'm still using Pharo 1.3 so I can use it, until the desire
 to use 2.0 and beyond finally pushes me into completing my porting
 effort ;)
 
 If you do want to give the porting a go yourself, I'd suggest posting
 to the Magma list.  Chris is very supportive of porting efforts.
 
 Regards,
 Stuart
 
 On 4 June 2013 22:32, Thushar G R thushar...@gmail.com wrote:
 Hi all,
 
 
 I am new here in this list. I have already asked this question in stack
 overflow, but not much luck. So i thought ill contact the gurus directly.
 
 I am considering Magma to be used for one of my projects , which is nothing
 but a custom game center to connect my game and store user details and
 retrieve it. This would be the first time that i will be using pharo for one
 of my projects ( in fact this is the first time that i am able to decide for
 my self - the client has not preferences in terms of technology selection).
 
 So my concern is this, is Magama upgraded to be used in Pharo 2.0? What if i
 load it  and change the SystemChangeNotifiers with SystemAnnouncer and so on
 , will it cause any trouble in the future. I Appreciate any comments for
 this.
 
 
 Regards
 
 thushar