Package extension. Adding instance variables to classes

---------- Přeposlaná zpráva ----------
From: Alidra Abdelghani <[hidden email]>
To: [hidden email]
Cc: 
Bcc: 
Date: Mon, 7 May 2018 11:25:49 +0100
Subject: Package extension. Adding instance variables to classes

Hi,

I am working on a package named ClassNamesAnalyzer and I need to add code to third party classes in other packages (for instance the FAMIX-Core package).

“Extending” third party classes with methods is easy; I just need to categorise my methods under the *ClassNamesAnalyzer protocole so that loading my package will load them in the image.

However, if I want to add instance variables to theses classes, they are not there when I load the package in a new image.

So my question is : is there a way to include instance variables addition to other packages in my package?

Another question is : is it good practice to add instance variables to classes in third party packages and is there a way to avoid it (because I am not very confortable with that idea)?

Thanks in advance,

Abdelghani

Guillermo Polito wrote:

Just be careful, that privateState thing looks like a Moose only Famix feature. It't not available in plain Pharo objects :)

In ES6 mailing list, they had this problem re how to do private state for objects, and it was shown that having private state is sort of isomorphic to having WeakMap indexed by objects. So in case of Pharo, I'd say using WeakIdentitityKeyDictionary can do the trick. Without resorting to any external dependency.

Herby

On Wed, May 9, 2018 at 2:09 AM, Alidra Abdelghani via Pharo-users <[hidden email] <mailto:[hidden email]>> wrote:



    ---------- Forwarded message ----------
    From: Alidra Abdelghani <[hidden email]
    <mailto:[hidden email]>>
    To: Pavel Krivanek <[hidden email]
    <mailto:[hidden email]>>
    Cc: Any question about pharo is welcome <[hidden email]
    <mailto:[hidden email]>>
    Bcc:
    Date: Wed, 9 May 2018 01:09:06 +0100
    Subject: Re: Package extension. Adding instance variables to classes
    Hi Pavel,

    Thank you for your answer.
    I actually didn’t know about this mechanism.
    I think it is will do the job :)
      I have probably to rewrite some parts pf my code to access my
    variables through privateState.  no?


    Thanks again
    Abdelghani

    On 07 May 2018, at 13:15, [hidden email]
    <mailto:[hidden email]> wrote:


    Message: 1
    Date: Mon, 7 May 2018 13:43:56 +0200
    From: Pavel Krivanek <[hidden email]
    <mailto:[hidden email]>>
    To: Any question about pharo is welcome
    <[hidden email] <mailto:[hidden email]>>
    Subject: Re: [Pharo-users] Package extension. Adding instance
    variables to classes
    Message-ID:
    <CAHN2FzeMiBL4Y8asJ0XCjS2AQdxycoN+pbc+Hsd=[hidden email] <mailto:[hidden email]=[hidden email]>>
    Content-Type: text/plain; charset="utf-8"

    2018-05-07 12:25 GMT+02:00 Alidra Abdelghani via Pharo-users <
    [hidden email] <mailto:[hidden email]>>:

    ---------- P?eposlan? zpr?va ----------
    From: Alidra Abdelghani <[hidden email]
    <mailto:[hidden email]>>
    [hidden email] <mailto:[hidden email]>
    Cc:
    Bcc:
    Date: Mon, 7 May 2018 11:25:49 +0100
    Subject: Package extension. Adding instance variables to classes
    Hi,

    I am working on a package named ClassNamesAnalyzer and I need to
    add code
    to third party classes in other packages (for instance the FAMIX-Core
    package).
    ?Extending? third party classes with methods is easy; I just need to
    categorise my methods under the *ClassNamesAnalyzer protocole so that
    loading my package will load them in the image.
    However, if I want to add instance variables to theses classes,
    they are
    not there when I load the package in a new image.

    *So my question is* : is there a way to include instance variables
    addition to other packages in my package?

    Currently not, you should use privateState

    *Another question is* : is it good practice to add instance
    variables to
    classes in third party packages and is there a way to avoid it
    (because I
    am not very confortable with that idea)?

    It is not, see FAMIXContainerEntity>>#definedAnnotationTypes how
    this issue
    is currently being solved using the privateState.

    Cheers,
    -- Pavel

    Thanks in advance,
    Abdelghani

--

       

Guille Polito

Research Engineer

Centre de Recherche en Informatique, Signal et Automatique de Lille

CRIStAL - UMR 9189

French National Center for Scientific Research - _http://www.cnrs.fr_


*Web:* _http://guillep.github.io_

*Phone: *+33 06 52 70 66 13