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RE: Comments on the diagram (was: RE:[Pyatcron-devel-list]Cronbackend: a

Subject: RE: Comments on the diagram (was: RE:[Pyatcron-devel-list]Cronbackend: a correction)
Date: Tue, 18 Nov 2003 16:22:18 +0100

Yes, that's it, sorry for not being enough clear ;-)

> -----Message d'origine-----
> De : address@hidden
> [mailto:address@hidden
> la part de Julien Olivier
> Envoyé : mardi, 18. novembre 2003 12:43
> À : address@hidden
> Objet : RE: Comments on the diagram (was:
> RE:[Pyatcron-devel-list]Cronbackend: a correction)
> > No, the two classes shouldn't be merged, there is a simple 
> reason for that.
> > If I do the merge, then I will have a single object that 
> will return the time entry and the exec command of the task. 
> Let's imagine how the software will have to be designed with 
> one Task class:
> > 
> > I remind you that we have to manage Cron and At deamon, 
> which use very different timing structure. So, the Task class 
> will have to deal with Cron entries and At system calls. 
> > Ok, at this points everything sounds good.
> > Now, have a look at specialized task. We want to make an 
> ArchiverTask. We simply inherit from Task and override the 
> "getCommand" method. But hey, this is wrong, a Task doesn't 
> know about Cron an At, we must inherit from CronTask and AtTask.
> > This sounds wrong, as we will have to maintain an 
> ArchiverCronTask and an ArchiverAtClass, which in OO approach 
> is fully wrong.
> > 
> > Note that when working with class diagram, we are not 
> designing databases. Even if you have a (1,1) relation, you 
> have to consider also your inheritance path.
> > 
> > Hope that my explanation are enough clear for all of you. 
> Do not hesitate to send remarks if needed.
> > 
> Just to be sure, what you are saying is that, if we merge those 2
> classes, each task type class would have to be whether a CronTask or
> AtTask (by inheritance) explicitly, which would be bad. Is 
> that it ? If
> that's it, I agree with you.
> -- 
> Julien Olivier <address@hidden>
> _______________________________________________
> Pyatcron-devel-list mailing list
> address@hidden

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