On 08Nov2017 10:28, Antoine Pitrou <solip...@pitrou.net> wrote:
On Wed, 8 Nov 2017 13:07:12 +1000
Nick Coghlan <ncogh...@gmail.com> wrote:
On 8 November 2017 at 07:19, Evpok Padding <evpok.padd...@gmail.com> wrote:
> On 7 November 2017 at 21:47, Chris Barker <chris.bar...@noaa.gov> wrote:
>> if dict order is preserved in cPython , people WILL count on it!
>
> I won't, and if people do and their code break, they'll have only themselves
> to blame.
> Also, what proof do you have of that besides anecdotal evidence ?
~27 calendar years of anecdotal evidence across a multitude of CPython
API behaviours (as well as API usage in other projects).
Other implementation developers don't say "CPython's runtime behaviour
is the real Python specification" for the fun of it - they say it
because "my code works on CPython, but it does the wrong thing on your
interpreter, so I'm going to stick with CPython" is a real barrier to
end user adoption, no matter what the language specification says.
Yet, PyPy has no reference counting, and it doesn't seem to be a cause
of concern. Broken code is fixed along the way, when people notice.
I'd expect that this may be because that would merely to cause temporary memory
leakage or differently timed running of __del__ actions. Neither of which
normally affects semantics critical to the end result of most programs.
However, code which relies on an ordering effect which works in the usual case
but (often subtly) breaks in some unusual case can be hard to debug, because
(a) recognising the salient error situation may be hard to do and (b) reasoning
about the failure is difficult when the language semantics are not what you
thought they were.
I think the two situations are not as parallel as you think.
Cheers,
Cameron Simpson <c...@cskk.id.au> (formerly c...@zip.com.au)
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