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bpo-46120: State that | is preferred over Union #30222

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Dec 24, 2021
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bpo-46120: State that | is preferred over Union #30222

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sobolevn Dec 22, 2021
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Update Misc/NEWS.d/next/Documentation/2021-12-21-12-45-57.bpo-46120.P…
gvanrossum Dec 24, 2021
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2 changes: 1 addition & 1 deletion Doc/library/typing.rst
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Expand Up @@ -625,7 +625,7 @@ These can be used as types in annotations using ``[]``, each having a unique syn

Union type; ``Union[X, Y]`` is equivalent to ``X | Y`` and means either X or Y.

To define a union, use e.g. ``Union[int, str]`` or the shorthand ``int | str``. Details:
To define a union, use e.g. ``Union[int, str]`` or the shorthand ``int | str``. Using that shorthand is recommended. Details:

* The arguments must be types and there must be at least one.
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arguments are only present when using the Union[X, Y] syntax. Prepend a clarification on this "When using Union[] syntax, the arguments ..."

Add something that covers what may be |ed together. "Only types may be used with the | operator for this purpose" or similar perhaps.

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This text is technically in the "module contents" section. There is more on X|Y in the docs for the types module. Maybe we could link there (on the word "shorthand") like was done in the first version of this PR. If the description of X|Y there is not clear enough it should be updated there IMO.

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Crosslinking shorthand does make sense. Otherwise I think the text here is clear enough as is.


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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Documentation/2021-12-21-12-45-57.bpo-46120.PE0DmJ.rst
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State that ``|`` is preferred for readability over ``Union`` in the :mod:`typing` docs.