Using the REPL (Read-Evaluate-Print Loop)

The REPL allows you to interact with a running Pygame Zero game using Python commands. As you type it will offer suggestions based on variables that exist in your program. This can be useful for debugging your game or tuning how difficult it is.


REPL is short for a Read-Evaluate-Print Loop; it means:

  1. Read a line of code typed by you
  2. Evaluate the code
  3. Print the result
  4. Loop back to step 1!

This is an optional feature that may need to be installed if it was not originally installed with Pygame Zero. If you try using the REPL, Pygame Zero will let you know if it is not installed.

Running a Pygame Zero program with the REPL

If you normally run your Pygame Zero program using the terminal, add --repl to the command line when running pgzrun. For example, if your game is in a file called, run:

pgzrun --repl

Using the REPL

Python code that you type at the REPL is evaluated as if you had typed it into your game file.

For example, if your game file contains the code

alien = Actor('alien', pos=(54, 60))

def draw():

Then at the REPL you could type alien to see the alien object:

>>> alien
<Actor 'alien' pos=(54, 60)>

You can set attributes on the alien object and see it move:

>>> alien.x = 90