interactiveshell.py 文件源码

def init_virtualenv(self):
        """Add a virtualenv to sys.path so the user can import modules from it.
        This isn't perfect: it doesn't use the Python interpreter with which the
        virtualenv was built, and it ignores the --no-site-packages option. A
        warning will appear suggesting the user installs IPython in the
        virtualenv, but for many cases, it probably works well enough.

        Adapted from code snippets online.

        http://blog.ufsoft.org/2009/1/29/ipython-and-virtualenv
        """
        if 'VIRTUAL_ENV' not in os.environ:
            # Not in a virtualenv
            return

        # venv detection:
        # stdlib venv may symlink sys.executable, so we can't use realpath.
        # but others can symlink *to* the venv Python, so we can't just use sys.executable.
        # So we just check every item in the symlink tree (generally <= 3)
        p = os.path.normcase(sys.executable)
        paths = [p]
        while os.path.islink(p):
            p = os.path.normcase(os.path.join(os.path.dirname(p), os.readlink(p)))
            paths.append(p)
        p_venv = os.path.normcase(os.environ['VIRTUAL_ENV'])
        if any(p.startswith(p_venv) for p in paths):
            # Running properly in the virtualenv, don't need to do anything
            return

        warn("Attempting to work in a virtualenv. If you encounter problems, please "
             "install IPython inside the virtualenv.")
        if sys.platform == "win32":
            virtual_env = os.path.join(os.environ['VIRTUAL_ENV'], 'Lib', 'site-packages') 
        else:
            virtual_env = os.path.join(os.environ['VIRTUAL_ENV'], 'lib',
                       'python%d.%d' % sys.version_info[:2], 'site-packages')

        import site
        sys.path.insert(0, virtual_env)
        site.addsitedir(virtual_env)

    #-------------------------------------------------------------------------
    # Things related to injections into the sys module
    #-------------------------------------------------------------------------