| << Chapter < Page | Chapter >> Page > |
| Figure 2 . Output from the code in Listing 4. |
|---|
Tom
Joe |
Finally, the code in Listing 5 uses the reference to the Subclass object to modify and then print the value stored in the class variable of the Superclass class named superclassVar .
| Listing 5 . Modify and then print the value in superclassVar. |
|---|
ref.superclassVar = "Sue"
print(ref.superclassVar) |
Figure 3 shows the output produced by executing the code in Listing 5 .
| Figure 3 . Output from the code in Listing 5. |
|---|
Sue |
I encourage you to copy the code from Listing 6 . Execute the code and confirm that you get the same results as those shown in Figure 4 . Experiment with the code, making changes, and observing the results of your changes. Make certain that youcan explain why your changes behave as they do.
I also encourage you to create a visualization for the code in Listing 6 . Step through the program one instruction at a time. As you do that, pay attention to the movements of the red and green arrows on the left, the diagramon the right, and the printed material at the bottom. That should help you to better understand inheritance in Python.
A complete listing of the program discussed in this module is provided in Listing 6 below. The output produced by the code in Listing 6 is shown in Figure 4 .
| Listing 6 . Complete program listing. |
|---|
# Illustrates inheritance
#----------------------------------------------------------#Define the superclass
class Superclass(object):superclassVar = Truedef __init__(self,name):
Superclass.superclassVar = nameself.friend = "Tom"
#Define a subclass that extends or inherits from Superclassclass Subclass(Superclass):
def __init__(self,name):Superclass.__init__(self,name)
print(self.friend)#Code that exercises the classes
print(Superclass.superclassVar)ref = Subclass("Joe")
print(ref.superclassVar)ref.superclassVar = "Sue"
print(ref.superclassVar) |
| Figure 4 . Output from code in Listing 6. |
|---|
True
TomJoe
Sue |
This section contains a variety of miscellaneous information.
Financial : Although the Connexions site makes it possible for you to download a PDF file for thismodule at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, you should beaware that some of the HTML elements in this module may not translate well into PDF.
I also want you to know that, I receive no financial compensation from the Connexions website even if you purchase the PDF version of the module.
In the past, unknown individuals have copied my modules from cnx.org, converted them to Kindle books, and placed them for sale on Amazon.com showing me as the author. Ineither receive compensation for those sales nor do I know who does receive compensation. If you purchase such a book, please beaware that it is a copy of a module that is freely available on cnx.org and that it was made and published withoutmy prior knowledge.
Affiliation : I : I am a professor of Computer Information Technology at Austin Community College in Austin, TX.
-end-
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