Operation Manual

Experiments in Python

Notes:

Then you can use your arrow keys to move the cursor up to the line beginning with

“for” and then press Return, twice. If you are wondering why you need to press

Return twice; the ﬁrst time is to complete the “for” command. When you press the

second time, Python recognises you have ﬁnished that command and executes

what you have typed.

Now let’s get some real computer graphics going. Enter this:

>>> import pygame

After a couple of seconds you’ll see the prompt reappear.

>>> import pygame

>>>

Wow! You imported “PyGame”. So what is that, and what does it mean? Again,

don’t worry about that. You have just told Python that you want to use its game-

creation features. “Import” loads extra commands into Python that you can use

from now on.

A note about text colours

While you were typing “import pygame” you should have noticed

that the word “import” changed colour as soon as you ﬁnished

typing it. This is because IDLE has a feature called “syntax

highlighting”. The colouring isn’t required for any Python

program to work but it is helpful to programmers when reading

code. When the text of a program is highlighted with colours,

it makes it easier to spot mistakes.

For now, just think of it as the opposite of the little red squiggles

that mark spelling errors when you write an essay in a word

processor. It doesn’t point out errors, but highlights that IDLE

has recognised a key Python command.

Making an amazing game will take ages and lots of commands, but while we’re

building up to that, here are just a few more lines for you to type to see something

wonderful. Type these in exactly as you see below.

>>> deepblue = (26,0,255)

>>> mintcream = (254,255,250)

This has given some names to a couple of “tuples” for you to use later. These

tuples are just data for the computer, and it will be using them to create colours in

just a moment.

>>> pygame.init()

>>> size = (500,500)

>>> surface = pygame.display.set_mode(size)