Managing required packages in nALFS

Jamie Bennett jamie_bennett at pcpmicro.co.uk
Fri Sep 13 08:53:54 PDT 2002


> -----Original Message-----
> From: Vassili Dzuba [mailto:vassili.dzuba at wanadoo.fr]
> For the time being, the <check> handler aborts the processing
> if it is not satisfied, so there is no problem with many levels of
> dependencies ;-)
 
Yeah, I was writing a patch that would list _all_ packages that a 
particular profile depended on. Kind of like Gentoo's portage that
can do a pretend build i.e. show you what _will_ be installed if
you want to proceed. I quickly realised that some kind of 
recursion was needed to traverse dependencies rather than list 
just the one that were in the current profile.

> However, if we want to support the automatic build of the packages
> we depend on, i think it is not too difficult as the current 
> processing
> is already recursive.
> 
> The handler for the <check> element could do :
>     - check if the required package is available
>       - if yes return
>       - if no :
>         - retrieve in the XML tree the element corresponding to the
>            required package (that's the most difficult thing to to)
>         - process it as it were a child of the <check> element
> 

This relies on the fact that we need to read in _all_ profiles that are
available on the system rather than just the ones in the current profile.
I don't know how well this would work with lots (100's) of profiles?

> Of course, this simple algorithm requires that the processing of the
> package is not too dependant on the context.
> If we have:
> 
>    stage1
>       package1
>    stage2
>      package2
>        check package1
> 
> and if the stageinfo of stage1 and stage2 are different (e.g. chroot
> to different directories), we cannot simply interpret package1 in the
> context of package2  so that this situation should be avoided if
> we want automatic build of the required package.
> 
> And of course, the dependence graph shouldn't contain cycles
> (that are meaningless in this context but could crash the application)
> 

Agreed.

> Vassili

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