How to access python package metadata from within the python console?

问题

If I have built a python package employing distutils.core, e.g. via

setup(
    ext_package="foo",
    author="me",
    version="1.0",
    description="foo package",
    packages=["foo",],
)

where does all the metadata go (what is it intended for?) and how can I access it from within python. Specifically, how can I access the author information from the python console after doing something like

>>> import foo

回答1:

One way to access the metadata is to use pip:

import pip

package = [pckg for pckg in pip.get_installed_distributions() 
            if pckg.project_name == 'package_name'][0]
#  package var will contain some metadata: version, project_name and others.

or pkg_resources

from pkg_resources import get_distribution

pkg = get_distribution('package_name')  # also contains a metadata

回答2:

The metadata are stored inside the <package>-<version>-<py version>.egg-info file.

when you create your module, you should have this line :

Writing /usr/lib/python2.7/site-packages/foobar-1.0-py2.7.egg-info

This file contain the Metadata :

Metadata-Version: 1.0
Name: Foobar
Version: 1.0
Summary: foobar
Home-page: http://foobar.com/
Author: foobar
Author-email: foobar@foobar.net
License: UNKNOWN
Description: UNKNOWN
Platform: UNKNOWN

If you want to access it, the best way is with pip or pkg_resources (as said Alexander Zhukov) ex :

>>> import pkg_resources
>>> d = pkg_resources.get_distribution('Foobar')
>>> d.version
'1.0'
>>> d.location
'/usr/lib/python2.7/site-packages'

回答3:

Concerning the version metadata only, I found it quite unreliable to use the various tools available as most of them do not cover all cases. For example

built-in modules
modules not installed but just added to the python path (by your IDE for example)
two versions of the same module available (one in python path superseding the one installed)

Since we needed a reliable way to get the version of any package, module or submodule, I ended up writing getversion. It is quite simple to use:

from getversion import get_module_version
import foo
version, details = get_module_version(foo)

See the documentation for details.

回答4:

One use of this data is that it is displayed on Pypi (http://pypi.python.org/) if you were to publish your package there. One way to structure it is like so:

in the top level of your foo module:

__author__= "me"
__version__= "1.0"
__description__= "foo package"

in setup.py:

import foo
setup(

    author = foo.__author__,
    version = foo.__version__,
    description = foo.__description__,
    packages = ["foo",],

)

This way you only need to update your metadata in one place, and as the data is defined in your packages main module, it will be accessible from there.

回答5:

Given setup.py as follows:

from distutils.core import setup

setup(
    name         = 'TestApp',
    version      = '0.0.1',
    author       = 'saaj',
    py_modules   = ['app'],
    test_suite   = 'test'
)

For some scripting and automation without installing the package, where pip, easy_install and even setuptools don't provide command line options or public APIs for reading all metadata (e.g. test_suite), here's a little hacky way:

python3 -c "import sys, types; m = types.ModuleType('distutils.core'); \
    m.setup = lambda **kwargs: print(kwargs); \
    sys.modules['distutils.core'] = m; import setup"

This will print a dict of keyword arguments passed to setup().

{'author': 'saaj', 'version': '0.0.1', 'name': 'TestApp', 
    'test_suite': 'test', 'py_modules': ['app']}

You can replace print in the lambda to whatever output you need. If your setup.py imports setup() from setuptools, which is actually the recommended way, just replace "distutils.core" with "setuptools" in the snippet.

Formatted snippet follows:

import sys
import types

m = types.ModuleType('distutils.core')
m.setup = lambda **kwargs: print(kwargs)
sys.modules['distutils.core'] = m

import setup  # import you setup.py with mocked setup()

回答6:

With python3.8 around the corner, you might want to use the new importlib.metadata module to parse any installed package's metadata.

Getting the author information would look like this:

>>> from importlib import metadata
>>> metadata.metadata('foo')['Author']
'me'

Which is a lot more straight forward than the former ways.

来源：https://stackoverflow.com/questions/20683118/how-to-access-python-package-metadata-from-within-the-python-console

标签

python

distutils