Re: Bug#14927: dpkg-perl should be marked essential
[I CC this to the debian-devel mailing list.]
On 16 Nov 1997, James Troup wrote:
> Christian Schwarz <schwarz@monet.m.isar.de> writes:
>
> > Package: dpkg-perl
> > Version: 0.1-2
> >
> > The package should be marked `Essential: Yes' so that other packages
> > can use the Perl module in their preinst script (e.g. tetex-*).
>
> Say what? When was consensus reached about this on debian.devel[1]?
It was never my intention to bypass debian-devel. This bug report should
be considered as a request from myself. It certainly needs to be discussed
now.
The topic has been discussed several times now, for example on
Sep 5, debian-devel, "dpkg question: preinst run before Depends:?"
Sep 23, debian-policy, "perl-base"
Most people agreed with my arguments, but we didn't get a decision until
now.
> And why are we making a package essential just so tetex can install
> faster?
The question is wrong. Note, that I just mentioned tetex-* as an example.
We currently have dpkg and perl-base tagged `Essential' (perl-base will
show up in the archive soon). dpkg-perl provides an excellent interface
from Perl to the dpkg libraries and only has `Installed-Size: 32'.
I think dpkg-perl could be useful for other packages, too, that need to
check for old packages, etc.
So the point is not to `tag it essential just for tetex-*', but to provide
a "legal" way for any package to access dpkg's database without having to
access /var/lib/dpkg/* directly and without having to call `dpkg'.
Several other possibilities have already taken into account:
1. Making tetex-* pre-depend on dpkg-perl. (This might be another
solution.)
2. Including dpkg-perl in the `dpkg' package. (If I remember
correctly, Klee doesn't like this solution.)
3. Including dpkg-perl in the tetex-* packages. (Not a good idea!)
4. Change the tetex-* preinst scripts to access /var/lib/dpkg/*
directly (that's illegal, IMHO).
5. Continue to use the awfully slow `dpkg -l' in the tetex-* preinst
scripts.
> Wouldn't it be easier to improve the tetex scripts for a start? For
> example, tetex-bin, tetex-base, tetex-extra *all* check for the old
> packages, and what's worse they all check regardless of whether or not
> there is a suitably recent, installed and configured version of any of
> the three packages already installed. Yes the check is painfully
> slow, but it's run needlessly, if the scripts were more intelligent
> and the check was run once (or worse case three times), I think it
> would be a lot less problematic.
This would be a temporary fix but would not solve the problem completely.
> Also what apart from tetex is going to need dpkg-perl? Why, if you
> insist on using dpkg-perl, not have tetex-{base,bin,extra} Pre-Depend
> on dpkg-perl? I don't think we should bloat the small number of
> packages that are Essential with fluff like dpkg-perl.
Of course, a pre-dependency is just as fine as the `Essential' from the
view point of the tetex-* packages.
However, I think it's a "policy decision": We've already decided to
include perl-base in our base system and tag it `Essential' so every
package can make use of the basic perl stuff without any dependencies. And
since dpkg-perl is so small and provides a really "clean" way to access
dpkg's databases, I don't see any disadvantage of tagging it `Essential'.
Any comments are appreciated.
Thanks,
Chris
-- Christian Schwarz
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Debian GNU/Linux? schwarz@debian.org, schwarz@mathematik.tu-muenchen.de
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