How to use dynamic paths in Python instead of hard-coded paths

Using hard-coded paths can make code difficult to maintain since it will not be portable. This is especially true in server-side web development. To avoid hard-coded paths, dynamic paths should be used. Here is an example of how to use them effectively, across different modules.

The directory tree for the example is as follows:

The .py files and their locations, along with the variables contained within each and what they print to the standard output, demonstrates how to use dynamic paths. Store these in the locations shown in the diagram and run using “python locate.py”

locate.py

import os

import deeper_directory.py_mod_1 as py_mod_1
import deeper_directory.deepest_directory.py_mod_2 as py_mod_2

from deeper_directory import *
from deeper_directory.deepest_directory import *

print

LOCATE_PY_FILENAME = __file__
LOCATE_PY_DIRECTORY_PATH = os.path.abspath(os.path.dirname(__file__))
LOCATE_PY_PARENT_DIR = os.path.abspath(os.path.join(LOCATE_PY_DIRECTORY_PATH, ".."))

print "Filename of locate.py: " + LOCATE_PY_FILENAME
print "Filepath of locate.py: " + os.path.join(LOCATE_PY_DIRECTORY_PATH, LOCATE_PY_FILENAME)
print "Directory Path of locate.py: " + LOCATE_PY_DIRECTORY_PATH
print "Parent Directory Path of locate.py: " + LOCATE_PY_PARENT_DIR

print

print "Filename of py_mod_1.py: " + py_mod_1.PY_MOD_1_PY_FILENAME
print "Filepath of py_mod_1.py: " + os.path.join(py_mod_1.PY_MOD_1_PY_DIRECTORY_PATH, py_mod_1.PY_MOD_1_PY_FILENAME)
print "Directory Path of py_mod_1.py: " + py_mod_1.PY_MOD_1_PY_DIRECTORY_PATH
print "Parent Directory Path of py_mod_1.py: " + py_mod_1.PY_MOD_1_PY_PARENT_DIR

print

print "Filename of py_mod_2.py: " + py_mod_2.PY_MOD_2_PY_FILENAME
print "Filepath of py_mod_2.py: " + os.path.join(py_mod_2.PY_MOD_2_PY_DIRECTORY_PATH, py_mod_2.PY_MOD_2_PY_FILENAME)
print "Directory Path of py_mod_2.py: " + py_mod_2.PY_MOD_2_PY_DIRECTORY_PATH
print "Parent Directory Path of py_mod_2.py: " + py_mod_2.PY_MOD_2_PY_PARENT_DIR

print

 deeper_directory/py_mod_1.py

import os

PY_MOD_1_PY_FILENAME = __file__
PY_MOD_1_PY_DIRECTORY_PATH = os.path.abspath(os.path.dirname(__file__))
PY_MOD_1_PY_PARENT_DIR = os.path.abspath(os.path.join(PY_MOD_1_PY_DIRECTORY_PATH, ".."))

deeper_directory/deepest_directory/py_mod_2.py

import os

PY_MOD_2_PY_FILENAME = __file__
PY_MOD_2_PY_DIRECTORY_PATH = os.path.abspath(os.path.dirname(__file__))
PY_MOD_2_PY_PARENT_DIR = os.path.abspath(os.path.join(PY_MOD_2_PY_DIRECTORY_PATH, ".."))

NOTE: Remember to put an empty __init__.py file in each directory that contains a Python Module