New submission from Dubslow <buns...@gmail.com>:
In sequence comparisons, the enforcement of reflexivity of elements means that
only non-identical elements are actually compared. The docs then note, with
example, that non-reflexive elements thus always "compare" equal inside the
sequence.
This patch adds a second corollary, that non-orderable singletons (e.g.
None) will also not break sequence comparison.
Yes, the consequence is logically derivable from the statement "element
identity is compared first, and element comparison is performed only for
distinct elements", but the first example is given because "For non-reflexive
elements, the result is different than for strict element comparison, and may
be surprising", which also holds for the example I add here: different from
strict element comparison, which may lead to otherwise surprising results (it
sure was surprising to me when I expected a list with Nones to fail to compare,
hence why I went trawling through the docs). In the manner of the first
example, explicit is better than implicit, and (I believe) it will be helpful
for readers to have this second consequence demonstrated.
----------
assignee: docs@python
components: Documentation
messages: 306780
nosy: Dubslow, docs@python
priority: normal
severity: normal
status: open
title: Docs: add note about sequence comparisons containing non-orderable
elements
versions: Python 3.7
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue32118>
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