Concept: Naming and Variables#

Naming#

In the first chapter, you saw instructions like this:

world = miniworlds.World()

Here, the = sign does not have the same meaning as in mathematics.

First, the right side of the statement is executed. In this case, a TiledWorld() object is created.
Second, the created object is stored under the name world. You can later refer to this object using its name.

Names in programming have a special purpose: they act as storage for objects and data. By assigning a name to an object, you can reuse or modify it later.

Such names are called variables, because the data they refer to can change.

Simple Example#

a = 3
b = 2
c = a + b

You store values in a and b, and later use them to compute c. The result will be 5.

Variables can also be overwritten — the old value is lost:

a = 3
a = 2
c = a + a
print(c)

This prints 4, because a was overwritten with the value 2.

The World Object#

The World is an object that has various attributes and methods.

Attributes#

You can access attributes using dot notation: object_name.attribute_name

Example:

world.rows = 4

This sets the number of rows in the world to 4.

Methods#

Methods are actions an object can perform, for example: world.add_background() adds a background to the world.

You access methods with: object_name.method_name() Sometimes, arguments are passed in parentheses.