On Wed, Nov 15, 2017 at 5:37 PM, Nick Coghlan <[email protected]> wrote:
> On 16 November 2017 at 00:20, Jim J. Jewett <[email protected]> wrote: > >> I *think* the following will happen: >> >> "NewList[int]" will be evaluated, and __class_getitem__ called, so >> that the bases tuple will be (A, GenericAlias(NewList, int), B) >> >> # (A) I *think* __mro_entries__ gets called with the full tuple, >> # instead of just the object it is found on. >> # (B) I *think* it is called on the results of evaluating >> # the terms within the tuple, instead of the original >> # string representation. >> _tmp = __mro_entries__(A, GenericAlias(NewList, int), B) >> >> # (C) I *think* __mro_entries__ returns a replacement for >> # just the single object, even though it was called on >> # the whole tuple, without knowing which object it >> # represents. >> bases = (A, _tmp, B) >> > > My understanding of the method signature: > > def __mro_entries__(self, orig_bases): > ... > return replacement_for_self > > My assumption as to the purpose of the extra complexity was: > > - given orig_bases, a method could avoid injecting bases already listed if > it wanted to > - allowing multiple items to be returned provides a way to > programmatically combine mixins without having to define a new subclass for > each combination > > Thanks, this might provide an answer to my question about multiple mro entries here https://mail.python.org/pipermail/python-ideas/2017-November/047897.html ––Koos -- + Koos Zevenhoven + http://twitter.com/k7hoven +
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