Bug#183470: dpkg: can't dependencies be checked before overwriting?
On Wed, Mar 05, 2003 at 05:13:32PM +0100, Martin Quinson wrote:
> Ben Collins wrote:
> > It's a chain of events based on definitions. gnucap depends on libgcc1,
> > which by definition means that libgcc1 needs to be installed before
> > gnucap can be configured. That does not mean it needs to be installed
> > before gnucap is. That would be a pre-depends (a depend which must be
> > satisfied before a package is even unpacked).
> >
> > Making your change would break all installs, even with apt and dselect.
> >
> > It's not uncommon to make use of this as a feature, which is why we have
> > the difference between depends and pre-depends.
>
> I guess you missunderstood. I think that Dan wants the "unpacking
> replacement gnucap" line coming after the "dependency problem" check.
I think Ben understood perfectly. Moving the "dependency problem" check
before the unpack phase in the general case is a significant change in
semantics, and, as Ben explained, will break large upgrades.
However, dpkg could potentially do this only on --install: that is, make
the --install flag not be simply { --unpack; --configure; }, but instead
be { pre-emptive dependency check; --unpack; --configure; }. I assume
that apt uses --unpack and --configure separately so this wouldn't break
it.
Not sure, though.
--
Colin Watson [cjwatson@flatline.org.uk]
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