On Tue, Mar 5, 2019 at 2:38 AM Inada Naoki <songofaca...@gmail.com> wrote:
> On Tue, Mar 5, 2019 at 7:26 PM Steven D'Aprano <st...@pearwood.info> > wrote: > > > > On Sat, Mar 02, 2019 at 01:47:37AM +0900, INADA Naoki wrote: > > > > If the keys are not strings, it currently works in CPython, but it > may not work with other implementations, or future versions of CPython[2]. > > > > > > I don't think so. https://bugs.python.org/issue35105 and > > > https://mail.python.org/pipermail/python-dev/2018-October/155435.html > > > are about kwargs. I think non string keys are allowed for {**d1, > > > **d2} by language. > > > > Is this documented somewhere? > > It is not explicitly documented. But unlike keyword argument, > dict display supported non-string keys from very old. > > I believe {3: 4} is supported by Python language, not CPython > implementation behavior. > > > https://docs.python.org/3/reference/expressions.html#grammar-token-dict-display > I'd like to remove all doubt: {**d1} needs to work regardless of the key type, as long as it's hashable (d1 could be some mapping implemented without hashing, e.g. using a balanced tree, so that it could support unhashable keys). If there's doubt about this anywhere, we could add an example to the docs and to the PEP. -- --Guido van Rossum (python.org/~guido)
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