Overview
- The keyword class is fundamental to object oriented programming in Python.
- The class keyword is used to define any concept e.g., Complex Number, UI Window, Sparse Matrix and so on which are instantiated using their definitions.
- Methods and attributes can be defined for a class, which correspond to the behavior and state of an instance.
- Through class keyword a new user defined type is introduced into the Python Program.
- In Python, a concrete class defined is used to instantiate any number objects of the same type as the class.
- An abstract class acts as a base class for derived classes and provides a common abstraction or a common interface for the derived classes.
- In the picture below moulds of dolls are varying sizes are kept. Just like actual dolls are manufactured using these moulds the objects are instantiated using the classes.
Picture Courtesy: Joel Kramer
- Multiple inheritance is supported in Python through which a specialized concept or class is created by deriving from more than one class.
Example:
- This Python example defines a class NoteBook representing a primitive notebook.
- The Python program also instantiates the NoteBook class creating a NoteBook object.
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class NoteBook: myPageCount = 0; myTitle = ""; myCoverOpen = False myCurrentPage = 0;
def __init__(self, pageCount, title): self.myPageCount = pageCount self.myTitle = title
self.myCoverOpen = False self.myCurrentPage = 1
def FlipPage(direction): self.myCoverOpen = True self.myCurrentPage = self.myCurrentPage+1 # forward flip
nb = NoteBook(60, "Python Programming")
print("Page Count: %s"%(nb.myPageCount)) print("Page Title: %s"%(nb.myTitle))
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Output:
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Page Count: 60 Page Title: Python Programming |