[Python-ideas] Proposal: Moratorium on Python language changes

[geremy condra]

On Wed, Oct 21, 2009 at 12:42 PM, Guido van Rossum <guido at python.org> wrote:
> I propose a moratorium on language changes. This would be a period of
> several years during which no changes to Python's grammar or language
> semantics will be accepted. The reason is that frequent changes to the
> language cause pain for implementors of alternate implementations
> (Jython, IronPython, PyPy, and others probably already in the wings)
> at little or no benefit to the average user (who won't see the changes
> for years to come and might not be in a position to upgrade to the
> latest version for years after).
>
> The main goal of the Python development community at this point should
> be to get widespread acceptance of Python 3000. There is tons of work
> to be done before we can be comfortable about Python 3.x, mostly in
> creating solid ports of those 3rd party libraries that must be ported
> to Py3k before other libraries and applications can be ported. (Other
> work related to Py3k acceptance might be tools to help porting, tools
> to help maintaining multiple versions of a codebase, documentation
> about porting to Python 3, and so on. Also, work like that going on in
> the distutils-sig is very relevant.)
>
> Note, the moratorium would only cover the language itself plus
> built-in functions, not the standard library. Development in the
> standard library is valuable and much less likely to be a stumbling
> block for alternate language implementations. I also want to exclude
> details of the CPython implementation, including the C API from being
> completely frozen -- for example, if someone came up with (otherwise
> acceptable) changes to get rid of the GIL I wouldn't object.
>
> But the moratorium would clearly apply to proposals for anonymous
> blocks, "yield from" (PEP 380), changes to decorator syntax, and the
> like. (I'm sure it won't stop *discussion* of those proposals, and
> that's not the purpose of the moratorium; but at least it will stop
> worries elsewhere that such proposals might actually be *accepted* any
> time soon.)
>
> --
> --Guido van Rossum (home page: http://www.python.org/~guido/)

I can't disagree with the sentiment, and I wholeheartedly agree with
the idea that shifting the focus from language development to library
development is a good idea- but I would caution against making the
moratorium too hard-and-fast, or too long lasting, assuming that
the goal isn't to make it de facto permanent.

Towards that end, I'd also like to propose a very public, very
accessible 'sandbox' specifically for the development and testing of
new language features while the moratorium is in effect. Its goal
would be to keep interest in changes to core language design
ongoing by keeping the barrier to entry low, while simultaneously
separating it from core development. With any luck, it would mean
that when the moratorium lifts, Python will be able to take its pick
from the best of the language proposals, while still having given
other implementations the opportunity to study their behavior
"in the wild" for a period of months or years.

Geremy Condra