Return -1 and set an exception on error; return 0 if the iterator is
exhausted, and return 1 if the next item was fetched successfully.
Prefer this API to PyIter_Next(), which requires the caller to use
PyErr_Occurred() to differentiate between iterator exhaustion and errors.
Co-authered-by: Irit Katriel <iritkatriel@yahoo.com>
It is now considered a historical accident that e.g. `for` loops and the `iter()` built-in function do not require the iterators they work with to define `__iter__`, only `__next__`.
Fix PyAiter_Check to only check for the `__anext__` presense (not for
`__aiter__`). Rename `PyAiter_Check()` to `PyAIter_Check()`,
`PyObject_GetAiter()` -> `PyObject_GetAIter()`.
Co-authored-by: Pablo Galindo Salgado <Pablogsal@gmail.com>
I think that none of these API calls can fail, but only few of them are
documented as such. Add the sentence "This function always succeeds" (which is
the same already used e.g. by PyNumber_Check) to all of them.
The added parentheses around the PyIter_Next assignment suppress the following warning which gcc throws without:
```
warning: using the result of an assignment as a condition without parentheses [-Wparentheses]
```
The other change is a typo fix
Erlend E. Aasland
Jelle Zijlstra
Brett Cannon
Yury Selivanov
Pablo Galindo
Erlend Egeberg Aasland
Antonio Cuni
Vladimir Matveev
William Ayd
Serhiy Storchaka
Stéphane Wirtel
Raymond Hettinger
Georg Brandl