After rereading Koos' OP, I can now see that he was referring to a different kind of runtime type checking than I am interested in. There was a distinction I was unaware the core typing devs make between "typing-style types" and "classes" that I'll discuss further in the typing repo itself. Apologies for the digression.
- Lucas On Sun, Jun 25, 2017 at 11:13 AM, Koos Zevenhoven <k7ho...@gmail.com> wrote: > On Sun, Jun 25, 2017 at 8:47 PM, Lucas Wiman <lucas.wi...@gmail.com> > wrote: > >> > Yes, but then `isinstance(tuple(range(1000000)), Tuple[int, ...])` >> would be a difficult case. >> >> Yes, many methods on million-element tuples are slow. :-) >> >> Python usually chooses the more intuitive behavior over the faster >> behavior when there is a choice. IIUC, the objections don't have anything >> to do with speed. >> >> > Sure, performance cannot dictate everything. But if you look at, for > example, that multidispatch example I wrote in the OP, it would not be wise > to do that expensive check every time. Also, people don't expect an > isinstance check to be expensive. But looking at annotations, it is often > possible to get the desired answer without checking all elements in a tuple > (or especially without consuming generators etc. to check the types). > > -- Koos > >
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