Should the PVP be changed with regards to instances?

[Ganesh Sittampalam]

On 20/12/2011 16:12, Johan Tibell wrote:

> 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!
> 
> Thoughts?

I'd argue against this: users who write orphan instances typically have
no choice, even if they know it's problematic. Contrast this to the fact
that we do allow new exports, because a cautious user of the package can
avoid problems by explicitly listing what they import.

Major version bumps are indeed expensive, but IMO we should address the
problem at source by to making them cheaper - e.g. with automated
testing/reporting.

Ganesh