Can you please explain why a multi-part second-argument must be a tuple
and not any other form of collection-type?
The signature is: isinstance(object, classinfo)
leading to "classinfo" of:
1/ a single class/type, eg int
2/ a tuple of same, eg ( int, str, )
3/ a union type, eg int | str (v3.10+)
A question was asked about this at last night's PUG-meeting. The person
was using the union option, but from Python v3.8. Sorting that out, he
replaced the union with a list. No-go! Before correcting to a tuple...
Why does the second argument need to be a tuple, given that any series
of non-keyword arguments is a tuple; and that such a tuple will still
need to be delimited by parentheses. In other words, other forms of
delimiter/collection, eg list and set; being a series of
elements/members would seem no different.
Yes, the underlying C operation appears to only accept a single argument
(am not C-soned, mea culpa!).
There is some discussion about hashability, but isn't it coincidental
rather than constructive? (again, maybe I've not understood...)
Enquiring minds want to know...
Web.Refs:
https://docs.python.org/3/library/functions.html?highlight=isinstance#isinstance
https://docs.python.org/3/c-api/object.html?highlight=isinstance#c.PyObject_IsInstance
https://docs.python.org/3/reference/datamodel.html?highlight=isinstance
--
Regards,
=dn
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