In a __init__.py file of a package, I imported several files relying on a third party module in another path. To inform python of the path of the third party module, I add the path to sys.path, like this

# __init__.py
import sys
sys.path.append("path of the third party module")

from .file_in_the_package import ... # the file rely on the third party module

Every thing goes fine until I moved the sys.path.append to a separated file in the package, like this

# separated file imp.py
import sys
sys.path.append("path of the third party module")

# changed __init__.py
import imp
from .file_in_the_package import ... # the file rely on the third party module

in which the added "path of the third party module" can not be found in either __init__.py or file_in_the_package.py. However, things goes fine with from .imp import *.

Now, I'm just curious that in what situation the changed sys.path will be passed when import a file/package with sys.path changed?