Given recent developments (Pyrex release with new syntax and Arc's new
project) I think Cython should make some public website statements on
language policy and stability. I think these are already present in the
"community spirit", but we should make them very explicit.
Rough suggestions aimed for starting this thread:
- "Cython want to be a dynamic work in progress and so new language
features will happen quickly over the next year. *However*, each change
will be related to previously unavailable features and will have a
backwards-compatible syntax."
- If we need to break syntax backwards-incompatibly, it will be done by
the scheme discussed earlier: A "#lang: cython-ver" comment header.
Files without such a header will be compiled with the current ("v0.9")
syntax.
- Some decision should be made on Pyrex compatability. I think it should
either be flat out "the language looks like Pyrex because of its roots
but is *not* Pyrex", or, we should aim to correctly compile Pyrex
(including future changes) but do so only when "#lang: pyrex" is specified.
(Of course, any "lang" instruction would be command-line-overridable so
that existing Pyrex code could be built with a "--pyrex-mode" flag)
- We need a consistent keyword policy. I'm going to be controversial and
suggest that this will be "figure it out from context", because we aim
to compile any Python code. I.e.:
* Any Python keywords are also Cython keywords (which exact keywords
depends on the Python language level we are compiling)
* Any non-Python keywords are only keywords when used in a context
where they can mean a keyword instruction. That is, we should start
supporting Cython code like this:
cdef = 4
# Created cdef variable, does not alter behaviour of cdef keyword
We already support
final = 4
anyway... I think any new Cython keywords (over Python) are always used
in contexts where they could not be a variable name so I think this is
possible.
This is unusual, but because our aim is to go towards full Python
support, but still support Cython code, I think such a policy is a
possible compromise (the important thing is to have a solid, dependable
rule we follow).
Another possibility is to only allow
cdef = 4
when we are in (also on the idea-stage, from the #lang-thread) Python
mode (compiling a .py-file or having a "#lang: python" header).
--
Dag Sverre
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