在 Python 3.3 venv (OS X/Homebrew) 中安装分发

Question

我一直在尝试在我的 OS X 机器上启动并运行 Python 3.3 的内置“venv”模块。我已经使用 Homebrew 安装了 Python 3.3。

根据文档，创建和切换虚拟环境按您的预期工作：

$ python3 -m venv myvenv
$ source myvenv/bin/activate

我已经测试过这样的东西：

$ echo "YEAH = 'YEAH!'" > myvenv/lib/python3.3/site-packages/thingy.py
$ python
>>> import thingy
>>> print(thingy.YEAH)
'YEAH!'

但是当我尝试安装分发时，它根本不会放在正确的位置。由于某种原因，它坚持尝试安装到/usr/local/lib/python3.3/site-packages/，但失败并显示以下消息：

No setuptools distribution found
running install
Checking .pth file support in /usr/local/lib/python3.3/site-packages/
/Users/victor/myvenv/bin/python -E -c pass
TEST FAILED: /usr/local/lib/python3.3/site-packages/ does NOT support .pth files
error: bad install directory or PYTHONPATH

You are attempting to install a package to a directory that is not
on PYTHONPATH and which Python does not read ".pth" files from.  The
installation directory you specified (via --install-dir, --prefix, or
the distutils default setting) was:

    /usr/local/lib/python3.3/site-packages/

and your PYTHONPATH environment variable currently contains:

    ''

无论我尝试使用distribute_setup.py 安装还是直接使用源代码分发，都会发生这种情况。我什至尝试过使用--prefix=/Users/victor/myenv，但它仍然尝试将所有内容放入我的“全局”站点包中。

我无法弄清楚为什么会发生这种情况，但它在我的两台机器上是一致的。请注意，sys.prefix 报告了正确的路径（虚拟环境）。

这是 Homebrew 的问题吗？操作系统？蟒蛇 3.3？ venv?我？

Answer 1

这是 Homebrew 的一个问题，是的，但它现在可以使用 https://github.com/mxcl/homebrew/commit/0b50110107ea2998e65011ec31ce45931b446dab。

$ brew update
$ brew rm python3  #if you have installed it before
$ brew install python3
$ cd /tmp
$ which python3
  /usr/local/bin/python3
$ python3 -m venv myvenv 
$ source myvenv/bin/activate
$ wget http://python-distribute.org/distribute_setup.py  # may need brew install wget
$ python3 distribute_setup.py  
  ...
  Finished processing dependencies for distribute==0.6.45
  After install bootstrap.
  Creating /private/tmp/myvenv/lib/python3.3/site-packages/setuptools-0.6c11-py3.3.egg-info
  Creating /private/tmp/myvenv/lib/python3.3/site-packages/setuptools.pth

您会看到分发安装成功到 /tmp 目录。

Answer 2

这是因为homebrew 安装了 distutils 配置文件：

$ brew cat python3  | grep "Tell distutils" -A5
    # Tell distutils-based installers where to put scripts
    (prefix/"Frameworks/Python.framework/Versions/#{VER}/lib/python#{VER}/distutils/distutils.cfg").write <<-EOF.undent
      [install]
      install-scripts=#{scripts_folder}
      install-lib=#{site_packages}
    EOF

$ mv ~/.local/Frameworks/Python.framework/Versions/3.3/lib/python3.3/distutils/distutils.cfg ~/tmp/
$ cat ~/tmp/distutils.cfg 
[install]
install-scripts=/Users/gatto/.local/share/python3
install-lib=/Users/gatto/.local/lib/python3.3/site-packages
$ . venv/bin/activate
(venv) $ python distribute-0.6.36/distribute_setup.py
(venv) $ ls venv/lib/python3.3/site-packages/
distribute-0.6.36-py3.3.egg  easy-install.pth  setuptools-0.6c11-py3.3.egg-info  setuptools.pth 

请参阅 bugs.python.org 上的“distutils.cfg Can Break venv”问题。