4.10. Glossary
- attribute
- Some state or value that belongs to a particular object. For example,
tess has a color.
- canvas
- A surface within a window where drawing takes place.
- control flow
- See flow of execution in the next chapter.
- for loop
- A statement in Python for convenient repetition of statements in
the body of the loop.
- instance
- An object that belongs to a class. tess and alex are different
instances of the class Turtle
- invoke
- An object has methods. We use the verb invoke to mean activate the
method. Invoking a method is done by putting parentheses after the
method name, with some possible arguments. So
wn.exitonclick()
is
an invocation of the exitonclick
method.
- iteration
- A basic building block for algorithms (programs). It allows steps to be repeated. Sometimes called looping.
- loop body
- Any number of statements nested inside a loop. The nesting is indicated
by the fact that the statements are indented under the for loop
statement.
- loop variable
- A variable used as part of a for loop. It is assigned a different value
on each iteration of the loop, and is used as part of the terminating
condition of the loop,
- method
- A function that is attached to an object. Invoking or activating the
method causes the object to respond in some way, e.g.
forward
is
the method when we say tess.forward(100)
.
- module
- A file containing Python definitions and statements intended for use in
other Python programs. The contents of a module are made available to
the other program by using the import statement.
- object
- A “thing” to which a variable can refer. This could be a screen window,
or one of the turtles you have created.
- range
- A built-in function in Python for generating sequences of integers. It
is especially useful when we need to write a for loop that executes a
fixed number of times.
- sequential
- The default behavior of a program. Step by step processing of algorithm.
- state
- The collection of attribute values that a specific data object maintains.
- terminating condition
- A condition that occurs which causes a loop to stop repeating its body.
In the
for
loops we saw in this chapter, the terminating condition
has been when there are no more elements to assign to the loop variable.
- turtle
- A data object used to create pictures (known as turtle graphics).
Next Section - 4.11. Exercises