Virtual Packages and version numbering
This follows up a debian-bugs posting with the Subject
"Re: Bug#1712: Tex has no version number texbin does"
Erick Branderhorst <branderhorst@fgg.eur.nl> said:
> It might be usefull to let the provides packages have the same version
> number as the providing package, or if a specific version number is
> given in the provides line providing that version number.
Virtual packages were originally proposed, as I recall, to provide
a means for alternative packages which conflict with one another
but seek to provide the same facility to declare that they each
provide that facility so that other packages could declare
dependency on the facility rather than on the packages. An
example might be the conflicting smail and sendmail packages,
either of which would provide an MTA needed by other packages
(e.g., pine). Eric's suggestion wouldn't add any value to this
use of virtual packages, but wouldn't seem to do any harm either.
A quick browse through my /var/lib/dpkg/Status file turned up the
following:
Package: xlib
Provides: xR6shlib, xlibraries
Package: dvipsk
Provides: dvips
Package: texbin
Provides: tex
Package: libc
Provides: libc.so.4
Package: latex
Provides: latex
Package: ltxtool
Provides: ltxtool
Package: kpathsea
Provides: kpathsea
Package: info
Provides: info-browser
Package: mfbin
Provides: metafont
In practice, virtual packages seem to be actually being used to
provide one or more aliases for one single installing package
providing a facility which is not also provided by a conflicting
package. Eric's suggestion would seem to be useful in this use of
virtual packages.
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