62 lines
1.8 KiB
Plaintext
62 lines
1.8 KiB
Plaintext
The https://docs.python.org/3/library/stdtypes.html#iterator-types[iterator protocol] specifies that the ``++__iter__++`` method can only return an iterator, i.e. an object with a ``++__next__++`` and an ``++__iter__++`` method (because iterators are also iterable). Returning anything else than an iterator will raise a ``++TypeError++`` as soon as the iteration begins.
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Note that https://docs.python.org/3/tutorial/classes.html#generators[generators] and https://docs.python.org/3/tutorial/classes.html#generator-expressions[generator expressions] have both ``++__next__++`` and ``++__iter__++`` methods generated automatically.
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This rule raises an issue when the object returned by an ``++__iter__++`` method does not have a method ``++__next__++``.
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== Noncompliant Code Example
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----
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class MyIterable:
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def __init__(self, values):
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self._values = values
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def __iter__(self):
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return None # Noncompliant
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----
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== Compliant Solution
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----
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class MyIterable:
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def __init__(self, values):
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self._values = values
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def __iter__(self):
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return MyIterator(self._values)
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class MyIterator:
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def __init__(self, values):
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self._values = values
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self._index = 0
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def __next__(self):
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if self._index >= len(self._values):
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raise StopIteration()
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value = self._values[self._index]
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self._index += 1
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return value
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def __iter__(self):
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return self
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----
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== See
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* https://www.python.org/dev/peps/pep-0234/#python-api-specification[PEP 234 - Iterators]
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* https://docs.python.org/3/library/stdtypes.html#iterator-types[Python documentation - Iterator Types]
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ifdef::env-github,rspecator-view[]
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'''
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== Comments And Links
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(visible only on this page)
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include::comments-and-links.adoc[]
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endif::env-github,rspecator-view[]
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