[Python-Dev] RFC: PEP 509: Add a private version to dict (original) (raw)

Random832 random832 at fastmail.com
Fri Apr 15 17:07:26 EDT 2016

On Fri, Apr 15, 2016, at 16:41, Victor Stinner wrote:

If the dictionary values are modified during the loop, the dict version is increased. But it's allowed to modify values when you iterate on keys.

Why is iterating over items different from iterating over keys?

in other words, why do I have to write:

for k in dict: v = dict[k] ...do some stuff... dict[k] = something

rather than

for k, v in dict.items(): ...do some stuff... dict[k] = something

It's not clear why the latter is something you want to prevent.

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