python pth file import statements ineffective?

Question

The import statements executed from the pth files seem to execute fine. But I don't seem to be able to access any of the modules that are imported in this way.

What is this sorcery?

Answer 1

From your comments I'm guessing that you're getting NameError exceptions for some modules due to confusion about the purpose of .pth -files.

pth stands for path . The purpose is to add paths to sys.path (pythonpath - path that Python uses to find modules during import). See site module documentation .

The lines that start with import can contain any code but generally they modify sys.path . For example, setuptools machinery:

import sys; new=sys.path[sys.__plen:]; del sys.path[sys.__plen:]; p=getattr(sys,'__egginsert',0); sys.path[p:p]=new; sys.__egginsert = p+len(new)

Another common case is when .pth -files are used to implement "namespace" packages :

import sys,types,os; p = os.path.join(sys._getframe(1).f_locals['sitedir'], *('zope',)); ie = os.path.exists(os.path.join(p,'__init__.py')); m = not ie and sys.modules.setdefault('zope',types.ModuleType('zope')); mp = (m or []) and m.__dict__.setdefault('__path__',[]); (p not in mp) and mp.append(p)

.pth -files are not there to make module names appear in your code. To import some_module , add at the top of each module where you want to use it:

import some_module