Question
Answer and Explanation
The reason you cannot directly import packaging from pkg_resources is because packaging is not a submodule or attribute that is exposed by the pkg_resources module. The pkg_resources module, part of the setuptools package, is primarily designed for working with installed Python packages and their metadata. It provides tools for finding and managing resources associated with installed packages, but it doesn't include direct access to packaging functionality.
The packaging module, on the other hand, is a separate library that provides tools for parsing and working with version strings, like those used in Python packages. It is usually available as a standalone package named packaging, and it should be installed separately if you need to use it.
Here's a breakdown:
1. pkg_resources: This module, often used by setuptools, is aimed at managing installed packages. It helps in tasks such as finding installed packages, accessing their metadata, or their resource files. It is not meant for general version parsing or other packaging related activities.
2. packaging: This is a distinct library that specializes in parsing, comparing, and manipulating package versions. It provides classes and functions designed to handle version numbers according to PEP 440 (the Python version specification standard). This includes things like sorting version numbers, checking version compatibility, etc.
How to use 'packaging' correctly:
To use the packaging module, you must install it as an independent package. Usually this is done through pip.
First you need to install it via command line:
pip install packaging
Then, import and use it directly:
from packaging import version
v1 = version.parse("1.2.3")
v2 = version.parse("2.0")
print(v1 < v2)
In summary: If you are encountering import errors while trying to use the packaging module, ensure that you have installed the packaging library using pip and that you are importing it correctly as from packaging import something rather than trying to get it through pkg_resources.