Question

i can’t find who defined the '__path__',why '__path__' can be use.

import os
import sys
import warnings 
import ConfigParser # ConfigParser is not a virtualenv module, so we can use it to find the stdlib

dirname = os.path.dirname

distutils_path = os.path.join(os.path.dirname(ConfigParser.__file__), 'distutils')
if os.path.normpath(distutils_path) == os.path.dirname(os.path.normpath(__file__)):
    warnings.warn(
        "The virtualenv distutils package at %s appears to be in the same location as the system distutils?")
else:
    __path__.insert(0, distutils_path)#who defined me.???
    exec open(os.path.join(distutils_path, '__init__.py')).read()

Answer 1

You really need to read some Python documentation and learn the basics of the language.

I checked, and you seem to speak Chinese. Here are Python documentation resources in Chinese:

http://www6.uniovi.es/python/doc/NonEnglish.html#chinese

Now, to answer your question. I wasn’t sure what the answer was, so I used Google. I did a Google search for “Python __path__” and very quickly found:

http://docs.python.org/tutorial/modules.html

6.4.3. Packages in Multiple Directories

Packages support one more special
attribute, __path__. This is
initialized to be a list containing
the name of the directory holding the
package’s __init__.py before the code
in that file is executed. This
variable can be modified; doing so
affects future searches for modules
and subpackages contained in the
package.

While this feature is not often
needed, it can be used to extend the
set of modules found in a package.