Beginning Python, 3rd Edition（Chapter 10）
Batteries Included(CHAPTER 10)1. tell your interpreter where to look for the module by executing the following.
>>> import sys
>>> sys.path.append('/home/zhanglei')# In UNIX, you cannot simply append the string '~/python' to sys.path. You must use the full path (such as '/home/yourusername/python')
>>> sys.path #显示interpreter搜索的路径
2.you try to import it again,nothing happens.
>>> import hello
>>>
They are mostly meant to define things, such as variables, functions, classes, and so on.
And because you need to define things only once, importing a module several times has the same effect as
importing it once.
3.hello2.py
**************************
#!/usr/bin/env python
def hello2():
print 'hello2'
**************************
>>> import hello2
>>> hello2.hello()
4.hello3.py
**************************
#!/usr/bin/env python
def hello():
print 'hello,world!'
# A test:
hello()
**************************
5. pprint is a pretty-printing function, which makes a more intelligent printout.
>>> import sys, pprint
>>> pprint.pprint(sys.path)
As long as your module is located in a place like site-packages('/usr/lib/python2.7/site-packages'), all your programs will be able to import it.
6.PYTHONPATH:
The standard method is to include your module directory (or directories) in the environment variable PYTHONPATH(Environment variables are not part of the Python interpreter)
export PYTHONPATH=/home/zhanglei/python
Tab补全：pythonTab.py(/home/zhanglei/python)
export PYTHONPATH=$PATHPATH:~/python
import sys
import readline
import rlcompleter
import atexit
import os
# tab completion
readline.parse_and_bind('tab: complete')
# history file
histfile = os.path.join(os.environ['HOME'], '.pythonhistory')
7.To make Python treat it as a package,it must contain a file named __init__.py.
You can also nest packages inside other packages.
File/Directory Description
~/python/ Directory in PYTHONPATH
~/python/drawing/ Package directory (drawing package)
~/python/drawing/__init__.py Package code (drawing module)
~/python/drawing/colors.py colors module
~/python/drawing/shapes.py shapes module
import drawing # (1) Imports the drawing package
import drawing.colors # (2) Imports the colors module
from drawing import shapes # (3) Imports the shapes module
8.To find out what a module contains, you can use the dir function:
dir(copy)
(Several of these names begin with an underscore—a hint (by convention) that they aren’t meant to be used outside the module.)
9. from copy import *
you get only the four functions listed in the __all__ variable.
If you don’t set __all__, the names exported in a starred import defaults to all global names in the module that don’t begin with an underscore
10. help(copy.copy):
A docstring is simply a string you write at the beginning of a function to document it
>>> print(copy.copy.__doc__)
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