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modular programming

The transaction file is working great, too

When you open up the transactions.txt file, you see this
inside: The descriptions follow. (Note
The next 16 characters are the extra padding due to the
The first 7 characters the credit card number. “%16s” format specifier.)
are the price.

00035006432425412474321 WORKOUT

00001507649463856424326 DONUT

Both of the records, created by each of the POS programs, are now
correctly formatted. That’s because both programs are sharing the
same piece of code to save the transactions.

coffee_pos.py
Phew! I just heard from the
bank that transactions from
both of the POS systems went
through smoothly. That‛s a big
relief. Good job fixing it!

Looks like you saved the day.

Q: So modules are sort of like Q: So when I use import, it’s as if I Q: Do I have to use modules?

containers for functions, right? typed the code in the module directly
into my program? A: No, but the benefit of putting
A: It’s true that most modules are used shareable code into a module starts to
to store a collection of related functions. A: Yes, that’s a good way to think about pay off the second you use that module
However, it is perfectly acceptable to it. Using a shared module saves you from in another program. Sharing code with
put any code in a module, which is then having to type (or cut’n’paste) all that code modules is good programming practice.
executed whenever the module is imported yourself. Just import it and it’s there.
into your program.

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