Notes from Coursera Using Databases with Python by Prof. Charles Severance

Basic Structure / Syntax

class ClassName:
    x = 0

    def methodName(self):
        self.x = self.x + 1

anObj = ClassName()

anObj.methodName();

• self is a variable that is an alias to an instance.
• Each instance has to have one parameter if want objects to "talk" to each other.

type()

• type(anObj) returns something about the variable/object.

dir()

• dir(anObj) lists capabilities of a class.
• Items enclosed by underscores are reserved methods used by Python.

Object Lifecycle

• Objects are created, used and discarded
• Constructors are methods that sets up instance variables that have initial values.
• Destructors are rarely used.

class ClassName:

    def __init__(self, nam):
        self.name = nam

    def __del__(self):
        ...

Inheritance

• Using an existing class in which one inherits all the capabilities of an existing class. Other terms are extending the class.
• Syntax:

class Class1:
    x = 0
    name = ""
    def __init__(self,nam):
        ...
    def a_Method(self):
        ...

class Class2(Class1):
    ...