如果没有设置__version__变量,如何检查python包的版本

Question

我正在使用pyodbc,我想知道我正在使用它的版本.显然我不能使用,pyodbc.__version__因为可能没有设置变量.

我怎么能弄清楚包的版本？

Answer 1

它确实有版本信息,只需使用.version:

In [4]: pyodbc.version
Out[4]: '3.0.10'

pip show命令也会为你得到它:

In [54]: pip.main(["show","pyodbc"])
---
Metadata-Version: 1.1
Name: pyodbc
Version: 3.0.10
Summary: DB API Module for ODBC
Home-page: http://code.google.com/p/pyodbc
Author: Michael Kleehammer
Author-email: michael@kleehammer.com
License: MIT
Location: /usr/local/lib/python2.7/dist-packages
Requires: 
Classifiers:
  Development Status :: 5 - Production/Stable
  Intended Audience :: Developers
  Intended Audience :: System Administrators
  License :: OSI Approved :: MIT License
  Operating System :: Microsoft :: Windows
  Operating System :: POSIX
  Programming Language :: Python
  Programming Language :: Python :: 2
  Programming Language :: Python :: 3
  Topic :: Database
Out[54]: 0

您可以重定向stdout并解析输出:

import pip
import sys

if sys.version_info.major >= 3:
    from io import StringIO
else:
    from StringIO import StringIO


def get_version(package):
    f = StringIO()
    sys.stdout = f
    pip.main(["show", package])
    sys.stdout = sys.__stdout__
    return next((line.split(":", 1)[1].strip()
                 for line in f.getvalue().splitlines() if line.startswith("Version")), "No match")

但更简单的方法是使用pkg_resources,如果你看一下show的来源,你可以看到它是如何收集的:

from pip._vendor import pkg_resources

def get_version(package):
    package = package.lower()
    return next((p.version for p in pkg_resources.working_set if p.project_name.lower() == package), "No match")

要使用它,只需传递包名称:

In [57]: get_version("pyodbc")
Out[57]: '3.0.10'

In [58]: get_version("pandas")
Out[58]: '0.17.1'

In [59]: get_version("requests")
Out[59]: '2.9.1'

In [60]: get_version("foobar")
Out[60]: 'No match'

您可以使用与show命令类似的逻辑轻松扩展它以获取不同的信息.