On 06. 04. 22 9:23, Tim Felgentreff wrote:
Hi,
(I briefly commented also on the doc regarding this)
I’m probably misinterpreting the exact goals. I read “stable ABI for
everyone” and I’m thinking “what needs to happen to stay binary
compatible and working for a couple of decades at least”.
Well, the doc is more down to the ground than this thread can be :)
If that were
the goal, I think the ideas around HPy’s handles and it’s usage of a
context to get access to function pointers are most important, since
that will ensure that new APIs can be added and old ones removed without
breaking ABI. (This is very similar to how e.g. libraries like SDL deal
with the problem that distributors want to update the SDL library and
have it still work with 10 year old proprietary games).
In particular, even things like slots in types need to be opaque. An
optimizing runtime may want to use varying layouts for both types and
objects - allowing direct access into any runtime structures prevents
that. Exposed structures should not be used for any runtime objects,
only as specs for construction of those runtime objects.
With Python's current general API backwards compatibility policy (PEP
387), it wouldn't make much sense to make ABI guarantees that strong. In
reality you're likely to get DeprecationWarnings and runtime exceptions,
and will need to recompile extensions well before decades+-scale ABI
incompatibilities hit you.
IIUC, adopting HPy would break API: adding a context argument to all
functions would would be so massive a change, it'd be easier to just
call that HPy rather than Python C-API. And the doc I shared is for the
C-API.
(Perhaps CPython can even move to HPy and implement C-API as a veener on
top -- but I don't think the original C-API can go away in our lifetimes.)
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