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CHAPTER 5 ■ CONDITIONALS, LOOPS, AND SOME OTHER STATEMENTS 83
from somemodule import *
The latter should only be used when you are certain that you want to import everything
from the given module. But what if you have two modules each containing a function called
open, for example—what do you do then? You could simply import the modules using the first
form, and then use the functions as follows:
module1.open(...)
module2.open(...)
But there is another option: You can add an as clause to the end and supply the name you
want to use, either for the entire module:
>>> import math as foobar
>>> foobar.sqrt(4)
2.0
or for the given function:
>>> from math import sqrt as foobar
>>> foobar(4)
2.0
For the open functions you might use the following:
from module1 import open as open1
from module2 import open as open2
Assignment Magic
The humble assignment statement also has a few tricks up its sleeve.
Sequence Unpacking
You’ve seen quite a few examples of assignments, both for variables and for parts of data structures
(such as positions and slices in a list, or slots in a dictionary), but there is more. You can perform
several different assignments simultaneously:
>>> x, y, z = 1, 2, 3
>>> print x, y, z
1 2 3
Doesn’t sound useful? Well, you can use it to switch the contents of two (or more)
variables:
>>> x, y = y, x
>>> print x, y, z
2 1 3
Actually, what I’m doing here is called “sequence unpacking”—I have a sequence of values,
and I unpack it into a sequence of variables. Let me be more explicit: