On May 22, 2011, at 3:48 PM, Robert Xu wrote: > On Sun, May 22, 2011 at 15:06, Jeff Johnson <n3...@mac.com> wrote: >> >> The flags and tags are reserved but again, there's sharp disagreement >> about the need for weak dependencies ala SuSE. > >> >> At the time "weak dependencies" were added, there was concern >> for SLES 10 compatibility (still using downrev rpm at the time). >> > > So it is in rpm5 for the time being... > >> >> My disagreement is that you can add a "strength" parameter, >> and implement using an integer, where "strongest" maps >> onto an integer comparison. >> >> But who and how are the integers assigned? If done >> with external configuration, then rpm installs >> become indeterminate. If done statically in an external >> file that is shipped with rpm and never changed, then >> why is there a need for an external table? > > Well, why would a strength table be needed? I see weak > dependencies as a "just added functionality" item and > strong dependencies as a "required definitely". > > I'm not really sure I understood you correctly on that. > > btw openSUSE explains it in their old wiki... they should > move it to the new wiki: > > http://old-en.opensuse.org/Software_management/Dependencies >
There's nothing I heard when "weak depends" wad first implemented
years ago that isn't on that wiki.
I see no reason for anything _EXCEPT_ the usual PRCO Gang Of Four:
Provides:
Requires:
Conflicts:
Obsoletes:
SuSE (to be backwards compatible with SLES10) chose to do additional tags rather
than change anything.
The "weak" part is basically "best effort": if it fails ignore.
A "best effort" leads to indeterminism during installs/upgrades/erases,
and the additional tags forces all code using metadata from *.rpm packages
to be changed, creating instant "legacy compatibility" issues everywhere.
>>
>> I also dislie (and see no need) for Yet More Types of Dependencies.
>
> Well, that's true.
>
>> So why is there a need to architect "weak dependencies" for
>> an essentially mainteneance only hysterical enterprise distro
>> shipped by a single vendor?
>>
>> None of the "weak dependencies" are implemented anywhere outside
>> of SuSE afaik, including rpm.org.
>
>
> IIRC Mandriva also uses weak dependencies to a degree
> with Suggests and stuff. Might be wrong.
>
Nope. Mandriva uses RPMSENSE_MISSINGOK, which was the 1st attempt
at add Suggests: to RPM. SuSE "weak dependencies" directly followed
as a consequence of RPMSENSE_MISSINGOK.
ANd like 6 years later there is _STILL_ no consensus nor adoption
of any of Suggests: et al in any version of RPM.
There really isn't any need for Suggests et al, or there WOULD
be a widespread deployment of an implementation by now.
I personally think that "preferences" need to be targeted. All
this would/should/coulda/kinda/dowhatimean that is implied
by naive intrinsic meanings to the words "siggests" and "enhances"
and "recommends" hasn't either a strong enough semantic or an
industrial strength implementation to handle "preference" years
and years later.
You can of course make up whetever semantic one wishes, implement it, and then
claim
It Just Works!
on some blog.
73 de Jeff
>
> --
> later, Robert Xu
> ______________________________________________________________________
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