Re: When to use pre-depends?
maor@ece.utexas.edu (Guy Maor) wrote on 05.09.96 in <[🔎] Pine.SOL.3.93.960905130431.13405E-100000@brando.ece.utexas.edu>:
> Is the essentialness of a package a sufficient condition for using
> pre-depends?
I would (naively?) think that pre-depends must be used if (and only if)
the installation of the package, without having first completed
installation of the dependency, would break the installation process.
That is, it should be used iff a simple depends won't do the right thing.
The difference in functionality between depends and pre-depends, as I
understand it, are that a pre-depends guarantees that your package won't
even be *unpacked* unless the pre-depends is already completely installed.
On the other hand, a depends only guarantees that the other package will
be completely installed before *configuration* of your package starts.
So - if unpacking your package before completely installing the dependency
will break, then you obviously need pre-depends.
For example, IIRC, an elf dpkg needs a pre-dependency on libc5 for that
reason - unpacking a new elf dpkg over an a.out dpkg without having a
functioning libc5 means a completely broken dpkg - desaster!
On the other hand, unpacking an elf editor in the same situation means
that while your editor is now broken, you can still use dpkg to install
the library. A simple depends will obviously DTRT here.
Now, Ian, how badly did I miss the point?
MfG Kai
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