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Abstract Base Classes for Containers, collections.abc, was introduced in Python 3.3.In order to use abstract classes like MutableMapping or MutableSequence in Python 3.2 and below or Python 3.3+ in a similar way, you can use the following imports with Python version check at runtime:
2. In older versions of python, typing.Sequence is a generic version of collections.abc.Sequence, used for typing. In recent versions, both are generic and typing.Sequence is essentially deprecated. – joel. Jan 30, 2023 at 18:33. here is how Sequence is defined in typing: Sequence = _alias(collections.abc.Sequence, 1). So it is the same thing.
The collections library provides abstract classes and their subclasses such as MutableSequence and it's super class Sequence. What is the necessity of abstract methods in the subclasses which are then forced to be defined in classes inheriting from them. Why can't concrete methods be used instead? So what would their implementation be?
So any content of collections.abc that already exists in Python <= 3.2, including Python 2, is found in collections directly. To support all versions of Python, use a try/except block: try: # works in Python >= 3.3. import collections.abc as collections_abc. except ImportError: # Python <= 3.2 including Python 2.
Another commonly used workaround is to conditionally import from collections or collections.abc depending on the Python version being used. For instance, have a PY2 boolean and do: if PY2: from collections import Sequence else: from collections.abc import Sequence This boolean is usually obtained either using six: from six import PY2
49. As said in other answers, the issue is the deprecation of some aliases from collections.abc into collections from python 3.10. If you can't modify the importations in your scripts because of a third-party import, as a temporary workaround you can do the aliases manually before importing the problematic third-party lib.
Due to PEP 585 - Type Hinting Generics In Standard Collections, Python's standard library container types are also able to accept a generic argument for type annotations. This includes the collections.abc.Iterable class.
The abstract types in collections.abc are implemented using the top level abc module. dict is registered as a MutableMapping (which is a subclass of Mapping) and so the isinstance check will accept a dictionary as a Mapping even though Mapping isn't an actual base class for dict.
The collections.abc types overload the isinstance() and issubclass() operators to check if the object has the expected interface, without requiring true subclassing. See PEP 3119 which introduced abstract base classes; in particular the section on overloading those two functions for more. This is sort of the point of the collections.abc module ...
import config a = config.test_config('test.txt') NameError: global name 'collections' is not defined But if I copy paste the whole code from config.py to the top of test.py, and then use the function, then I have no error(See code below).