Object-Oriented Programming

Features supported

• Multiple inheritance
• Method overriding (all methods are virtual)

Features not supported

• Private and protected members (all methods and data attributes are public)
• Static members (class members) (all methods and data attributes belong to individual objects)
• Non-virtual methods (final methods)

Quirky features

• Child data attributes will override parent data attributes of the same name.
• Data attributes can override methods (consistent naming conventions are needed to avoid confusion of this sort).

Misc

• A method can call the method of a base class with the same name: BaseClassName.methodName(self, args).  This only works if the base class is defined or imported directly in the global scope.

Defining a class

class ClassName [(BaseClass [,BaseClass]*)] :
    dataName = value
    def methodName(self [, arg]*):
        suite
    def __standardMethodName__(self [, arg]*):
        suite

• __init__  # constructor (initializor method)
• __del__  # destructor (cleanup method)

class ParentClass:
    def __init__(self, x):
        self.x = x
    def __del__(self):
        del self.x
    def foo(self):
        pass

class ChildClass(ParentClass):
    def __init__(self, x, y):
        ParentClass.__init__(self, x)
        self.y = y
    def __del__(self):
        ParentClass.__del__(self)
        del self.y
    def foo(self):
        ParentClass.foo(self)

Creating an instance of a class

instanceName = ClassName( [arg [,arg]*] )

x = MyClass()
y = ChildClass(123, 456)

Disposing of an instance of a class

del instanceName

Related functions

• Returns true if object has an attribute called name.

• Gets the named attribute from object.
• If not found raises AttributeError exception, or returns default if specified.

• Sets the named attribute in object.
• Creates the attribute if it doesn't exist.

setattr(childClass, 'y', 789)

if hasattr(childClass, 'y'):
    print getattr(childClass, 'y')