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Merge branch 'master' of github.com:python/peps

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Eric V. Smith 2017-12-03 09:44:40 -05:00
parent 2d95971d98 966dd42678
commit 57ccf32901
1 changed files with 7 additions and 6 deletions
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pep-0505.txt
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@ -613,13 +613,14 @@ those ideas are recorded here.
The ``None``-aware syntax applies to attribute and index access, so it seems The ``None``-aware syntax applies to attribute and index access, so it seems
natural to ask if it should also apply to function invocation syntax. It might natural to ask if it should also apply to function invocation syntax. It might
be written as ``foo?()``, where ``foo`` is only called if it is not None. This be written as ``foo?()``, where ``foo`` is only called if it is not None.
idea was quickly rejected, for several reasons.
First, no other mainstream language has such syntax. Second, Python evaluates This has been rejected on the basis of the proposed operators being intended
arguments to a function before it looks up the function itself, so to aid traversal of partially populated hierarchical data structures, *not*
``foo?(bar())`` would still call ``bar()`` even if ``foo`` is ``None``. This for traversal of arbitrary class hierarchies. This is reflected in the fact
behaviour is unexpected for a so-called "short-circuiting" operator. that none of the other mainstream languages that already offer this syntax
have found it worthwhile to support a similar syntax for optional function
invocations.
``?`` Unary Postfix Operator ``?`` Unary Postfix Operator
~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~