Python Cookbook 2Nd Edition Jun 1002005 [Electronic resources] نسخه متنی

Recipe 2.20. Finding a File on the Python Search Path

Credit: Mitch Chapman

Problem

A large Python application includes
resource files (e.g., Glade project files, SQL templates, and images)
as well as Python packages. You want to store these associated files
together with the Python packages that use them.

Solution

You need to be able to look for either files or directories along
Python's sys.path:

import sys, os
class Error(Exception): pass
def _find(pathname, matchFunc=os.path.isfile):
for dirname in sys.path:
candidate = os.path.join(dirname, pathname)
if matchFunc(candidate):
return candidate
raise Error("Can't find file %s" % pathname)
def findFile(pathname):
return _find(pathname)
def findDir(path):
return _find(path, matchFunc=os.path.isdir)

Discussion

Larger Python applications consist of sets of Python packages and
associated sets of resource files. It's convenient
to store these associated files together with the Python packages
that use them, and it's easy to do so if you use
this variation on the previous Recipe 2.18 to find files or directories
with pathnames relative to the Python search path.

See Also

Recipe 2.18; documentation
for the os module in the Library
Reference and Python in a
Nutshell.