1. Nate Brunelle Today: Functions again, Scope
CS1110
Nate Brunelle
Today: Functions again, Scope

2. Questions?

3. Last Time
Functions

4. Advice on functions Define function in one file, use in another
Good names
Usually an action phrase
You usually don’t want functions with side effects
Don’t use print, instead return a str
Don’t use input, instead use parameters
Use docstrings
Tell you why a function exists
How to use that function

5. Visualizing Programs

6. Scope Scope- The area where a variable has meaning
Usually: variable is in scope when it is created onward.
Functions: variable is in scope only in the function in which it is defined

7. What happens when you invoke a function?
Create memory for the function
Copy argument values into parameter names
Do what the function says
Know what to return, then return it
Remove the memory for the function

8. Which variable v is in scope?
If the variable v is available in the local scope, use that one
If the variable v is not available in the local scope, use the variable v available in the global scope
If a function ever will have the local variable v, you can only use that variable v

9. Global variables
Allow you to have something “remembered” from one run of a function to another.