Should the PVP be changed with regards to instances?

John Lato jwlato at
Wed Dec 21 12:12:20 CET 2011

> From: Johan Tibell <johan.tibell at>
> Hi,
> I find myself reluctant to add new instances to the unordered-containers
> package, because doing so would require a major version bump according to
> the PVP. Major version bumps are annoying for several reasons:
>  * Libraries that depend on unordered-containers need to be updated and
> make new releases.
>  * We get rapid successions of major releases without many actual changes
> (i.e. none as far as most users are concerned).
> Introducing new instances is unlikely to break users, as they will only get
> into trouble if they use orphan instances, which is already asking for
> trouble!

I'm in the same situation, however I'm quite hesitant to add new
instances in a minor version.  Adding new dependencies can cause
breakage even without orphan instances, if downstream packages import
a different version of that dependency already.

Practically this may be an acceptable short-term solution, but I agree
with Ganesh that major version bumps should be made less painful.

I've never really liked the PVP anyway as it relies upon a (rather
shaky, it now appears) convention.  I'd much prefer an automated
solution that uses exported/declared interfaces (autoconf is right in
principle).  I would contribute towards a system like that to replace
the PVP and version number-based dependencies as a long-term goal.

John L.

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