Python Learning Notes (v)-modules

I. Using modules

Introducing the SYS module, using the Import

#!/usr/bin/env python#-*-coding:utf-8-*-' a test module ' __author__ = ' Michael Liao ' import sysdef Test ():    args = s YS.ARGV    If Len (args) ==1:        print ' Hello, world! '    Elif len (args) ==2:        print ' Hello,%s! '% args[1]    else:        print ' Too many arguments! ' If __name__== ' __main__ ':    Test ()

Running Python hello.py Michael gets the sys.argv is [' hello.py ', ' Michael ']

Variables that use underscores _ as prefixes in Python are private variables and can only be used inside the module.

Variables such as __xx__ are special variables, and our own variables do not typically use this variable name.

Two. Installing a third-party module

When we try to load a module, the Python parser searches the current directory, all installed built-in modules, and third-party modules, and the search path is stored in the PATH variable of the SYS module.

>>> Import sys>>> Sys.path

If we want to add our own search directory, there are two ways:

1. Directly modify the Sys.path, add the directory to be searched Sys.path.append ('/users/imchael/my_py_scripts ')

This method is modified at run time and expires after the run is finished

2. Set the environment variable Pythonpath

Three. Using __future__

Since subsequent versions of Python are often incompatible with the previous version, in order to smooth the transition to a new version, Python provides a __future__ module that lets you experiment with some features of the new version in the old version:

If you want the ring to use python3.x's division in the python2.7 code, you can use the Division implementation of the __FUTURE__ module:

From __future__ import divisionprint ' 10/3 = ', 10/3  # 10/3 = 3.33333333333print ' 10.0/3 = ', 10.0/3  # 10. 0/3 = 3.33333333333print '//3 = ', +//3  # 10//3 = 3

Python Learning Notes (v)-modules