On Tue, 15 Sep 2020 at 09:22, Inada Naoki <songofaca...@gmail.com> wrote: > > On Tue, Sep 15, 2020 at 5:08 AM Marco Sulla > <marco.sulla.pyt...@gmail.com> wrote: > > > > 1. How can we check the size of an object only if it's an iterable > > using the Python C API? > > There is no good way. Additionally, we need to know distinct count if > we want to preallocate hash table. > For example, `len(dict(["foo"]*1000))` is 1, not 1000. > [...] > We have "one big resize" logic in dict_merge already. > And I use dummy empty dictkeys for new empty dict. > So we don't allocate any temporary, intermediate dictkey object.
Well, yes, but only for the first positional argument and if it's a map. I would be able to resize to the maximum possible size, that is len(arg) + len(kwarg). Of course the size can be overestimated, but I suppose the overlaps are very rare and small. The problem is that if I do this resize in dict_new, when the compilation does python -E -S -m sysconfig --generate-posix-vars a segfault happens. If I reintroduce the temporary dummy keys, it works. _______________________________________________ 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/AK35PRDPACXMHQ443CPB7GTYZXHTUQYV/ Code of Conduct: http://python.org/psf/codeofconduct/
