[Pharo-users] Updating a project and NIL class variables

Sven Van Caekenberghe sven at stfx.eu
Wed Jan 20 09:38:17 EST 2016


> On 20 Jan 2016, at 15:34, Dimitris Chloupis <kilon.alios at gmail.com> wrote:
> 
> Thank you for the info but I think I did not make myself clear because you say "remain nil"
> 
> Ok Imagine a class SomeClass and that class has a variable we will call SomeVariable, class variable that is
> , there is no class initialize method, now that class has a method that is eventually called , 
> someMethod
> 
> SomeVariable ifNil: [ SomeVariable := 'hello world']
> 
> so when I decide to update this class via metacello loading the latest version from github ,  SomeVariable will have the value 'hello world'
> 
> My question is , will SomeVariable after I do the update revert back to nil  or stay 'hello world' ? 
> 
> If your answer is no, and it stays 'hello world' then yes i need an initialize method and call it at update time. 

Argh, I should have said: keeps it value, will not revert to nil.

Sorry for the confusion !

> On Wed, Jan 20, 2016 at 2:54 PM Sven Van Caekenberghe <sven at stfx.eu> wrote:
> They remain nil.
> 
> That is why #initialize on the class side is needed.
> 
> You can call that explicitly in a post load script, or rely on the class loading mechanism that normally calls #initialize automatically when loading a class. The warning is: this only happens when the *source* code of the #initialize methods changes. So sometimes, you will have to touch that method to force it.
> 
> I hope that makes sense.
> 
> See MCMethodDefinition>>#postloadOver:
> 
> > On 20 Jan 2016, at 13:41, Dimitris Chloupis <kilon.alios at gmail.com> wrote:
> >
> > So my question is this , I have a class with nil variables that are lazy initialised only when needed the first time and of course they keep their values from there on.
> >
> > Lets say I get the latest update from github via metacello over an older update that I already have inside the image , do those variables revert back to nil values ? or do they keep their values as they are ?
> 
> 





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