Or perhaps:

  from experimental import new_module

This is kind of a guarantee that the interface will change; since at some point, if new_module is "calcified", this will have to be changed to just:

  import new_module

For experimental language features, maybe:

  from __experimental__ import new_feature

This makes it clear that new_feature may change (perhaps even not be adapted?), vs the from __future__ semantics.

Is it too complicated to try to differentiate between the decision of whether some capability will be provided or not, vs ironing out the API for that capability?

For example,

  from experimental import new_capability

means that there is no commitment for new_capability at all -- it may simply be dropped entirely.  The danger of using this is that new_capability may simply disappear completely with no replacement.


  from proposed import new_capability

represents a commitment that new_capability will be provided at some point, but the API will likely change.  Here the danger of using it is that you will likely have to change your program to conform to a new API.

A capability might start as "experimental", and if the value of it is demonstrated, move to "proposed" to work out the details before mainstreaming it.


On Mon, Jun 7, 2010 at 2:33 AM, Ron Adam <rrr@ronadam.com> wrote:

On 06/01/2010 08:22 PM, Brett Cannon wrote:

I can only see two scenarios that might be considered acceptable to
address these issues.

One is that when new modules are accepted into the stdlib they are
flagged with a ExpermintalWarning so that people know that no
backwards-compatibility promises have been made yet. That gets the
module more exposure and gets python-dev real-world feedback to fix
issues before the module calcifies into a strong
backwards-compatibility. With that experience more proper decisions
can be made as to how to change things (e.g. the logging module's
default timestamp including microseconds which strptime cannot parse).

Would it be possible to have a future_lib that gets enabled with something like...

  from __future__ import future_lib

These *new* library modules and packages won't be visible by default. Maybe they stay there until the next major version or possible some set period of time.


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