bpo-40636: Clarify the zip built-in docstring. (GH-20118)

Clarify the zip built-in docstring.

This puts much simpler text up front along with an example.

As it was, the zip built-in docstring was technically correct.  But too
technical for the reader who shouldn't _need_ to know about `__next__` and
`StopIteration` as most people do not need to understand the internal
implementation details of the iterator protocol in their daily life.

This is a documentation only change, intended to be backported to 3.8; it is
only tangentially related to PEP-618 which might offer new behavior options
in the future.

Wording based a bit more on enumerate per Brandt's suggestion.

This gets rid of the legacy wording paragraph which seems too tied to
implementation details of the iterator protocol which isn't relevant here.

Co-authored-by: Brandt Bucher <brandtbucher@gmail.com>
This commit is contained in:
Gregory P. Smith 2020-05-15 14:26:00 -07:00 committed by GitHub
parent 938717fd04
commit 6a5d3ff676
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2 changed files with 10 additions and 6 deletions

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@ -669,7 +669,7 @@ plain ol' Python and is guaranteed to be available.
True
>>> real_tests = [t for t in tests if len(t.examples) > 0]
>>> len(real_tests) # objects that actually have doctests
12
13
>>> for t in real_tests:
... print('{} {}'.format(len(t.examples), t.name))
...
@ -685,6 +685,7 @@ plain ol' Python and is guaranteed to be available.
2 builtins.int.bit_length
5 builtins.memoryview.hex
1 builtins.oct
1 builtins.zip
Note here that 'bin', 'oct', and 'hex' are functions; 'float.as_integer_ratio',
'float.hex', and 'int.bit_length' are methods; 'float.fromhex' is a classmethod,

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@ -2649,12 +2649,15 @@ static PyMethodDef zip_methods[] = {
};
PyDoc_STRVAR(zip_doc,
"zip(*iterables) --> zip object\n\
"zip(*iterables) --> A zip object yielding tuples until an input is exhausted.\n\
\n\
Return a zip object whose .__next__() method returns a tuple where\n\
the i-th element comes from the i-th iterable argument. The .__next__()\n\
method continues until the shortest iterable in the argument sequence\n\
is exhausted and then it raises StopIteration.");
>>> list(zip('abcdefg', range(3), range(4)))\n\
[('a', 0, 0), ('b', 1, 1), ('c', 2, 2)]\n\
\n\
The zip object yields n-length tuples, where n is the number of iterables\n\
passed as positional arguments to zip(). The i-th element in every tuple\n\
comes from the i-th iterable argument to zip(). This continues until the\n\
shortest argument is exhausted.");
PyTypeObject PyZip_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)