On Mar 12, 2020, at 12:02, Marco Sulla <mail.python....@marco.sulla.e4ward.com> wrote: > > On Thu, 12 Mar 2020 at 19:52, Andrew Barnert > <abarn...@yahoo.com.via.e4ward.com> wrote: >> I suppose it could track calls out to C functions as they happen and mark >> every value that was live before the call, and then instead of numpy >> checking refs==1 is could check refs==1 && !c_flagged, and then it wouldn’t >> need the C frame hackery. But that seems like it would slow down everything >> in exchange for occasionally helping numpy and a few other C extension libs. > > The author of the patch says this is already implemented in string > concatenation in Python itself. Maybe we should look at the > implementation, but I don't know where and what to search.
Strings, unlike numpy arrays, are immutable. (You can’t mutate them from Python; you can mutate them from the C API but it’s against the rules to do so after they’ve been shared with the interpreter.) And strings, unlike numbers (which numpy arrays act as), don’t have any C API functions that steal references. So they don’t require any kind of tracking or stack-fumbling. For a simpler parallel: the CPython compiler can merge two strings into a single object, and the CPython interpreter can intern strings at runtime, because this is guaranteed to be safe, but obviously neither can do the same thing for arbitrary objects. _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/Y5JNE2MCTCQMKJCXWOZFFKGWOBA6Q3HY/ Code of Conduct: http://python.org/psf/codeofconduct/
