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modular programming

So how do you create a module...?

Remember: a module is just a file containing some Python code. So, take the
code that you want to share out of the gym_pos.py file:

def save_transaction(price, credit_card, description):
file = open("transactions.txt", "a")

Then save this code in a file called transactions.py. You have just
created a new module.

...and how do you use it?

Once you’ve created the module, you then need to tell the programs to use it.
When you were using library code you needed to import it. You do the same
thing with your own modules. So, instead of using library code from the
Standard Python Library, you’re really just using library code that you’ve
written yourself. You can add this line to the top of each of your programs:

This means “run the code in

This line needs to be added the named module."
to any program that uses the This means “treat everything inside
“transactions.py” module. from transactions import * the module as if it is code within
your program."

With this line, you are telling Python that you want to run the code in the
transactions.py file and this allows you to access whatever code the
module contains as if it is just part of your program.

It’s time to fix the programs.

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