Functions and Code Reuse

Procedures and Code Reuse
cs 195/107 Notes

A procedure is a named sequence of blocks
.

Define it, then call it

once you define a procedure, you can call it from anywhere in your program.


Why would I define a procedure?
  • Compartmentalize code that you need more than once.
  • Copy-Paste leaves multiple copies of the same blocks.
    • if something changes, you have to change all copies.
  • For large software projects, break down a program hierarchically.
  • A procedure is an abstraction. Procedures let you ignore details as you design your program.
  • Sharing code blocks amongst apps (can't really do this with App Inventor)

DEMO: MakeQuiz app and displaying a list


Procedure Parameters: the information the procedure needs to do its job.

What parameters might you define for displaying a list?

Sketch the blocks for a procedure Move, which moves a ball a certain amount in the x and y direction. Hint:
you'll call MoveTo within it.



DEMO: Distance between two GPS coordinates