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identity confusion

The two discount functions have the

same name

Here is the promotion.py module you just created:

def discount(price):
return 0.9 * price

And here is the starbuzz.py module:

# Official Starbuzz Discount Module
# Copyright(c) Starbuzz Corporation
# All Rights Reserved.
# This function calculates a 5% discount on a price
def discount(price):
return 0.95 * price

Both of the modules define a function called discount(). So what
happens when you try to use them? If Python sees a line of code like
this:
new_price = discount(1.75)

which function will it call? The promotion discount? The Starbuzz
discount? Both? Neither???
This is one of the problems of using shared code. Sometimes, there’s
a function in one module that has the same name as a function in
another module. When this happens, the last function imported is the
one used, which has the effect of overloading any existing function
that has the same name. This can result in to hard-to-find bugs.
So what do you do?

You need to somehow qualify your function names.

206 Chapter 6