OOP in Python: Gist for my blogpost at gokul-uf.github.io

oop.py

'''References:
	1. https://developer.mozilla.org/en-US/Learn/Python/Quickly_Learn_Object_Oriented_Programming#start
	2. http://stackoverflow.com/questions/576169/understanding-python-super-with-init-methods
	3. http://www.artima.com/weblogs/viewpost.jsp?thread=236275
	4. https://docs.python.org/2/glossary.html#term-new-style-class
'''

class A:
#public attributes
	intAttribute = 0
	charAttribute = 'a'
	__hiddenAttribute = 'shh!'

  #Python does not have private attributes, it makes do with name-mangling which automatically prefixs the
  #Class Name to variable names which start with __ (double underscore.
  #To access it, use 
  #instanceName._className__attrName
  #This is called name-mangling
  #REF: https://docs.python.org/2/tutorial/classes.html#private-variables-and-class-local-references

  #public method, dummy getters and setters
  #NOTE self is a variable which refers to the current object; needed for context
	def getIntAttribute(self):
		return self.intAttribute
	
	def setIntAttribute(self,value):
		if type(value) is int:
			self.intAttribute = value
		else:
			raise TypeError
	def __init__(self): #Constructor
		intAttribute = -1
		charAttrribute = 'b'
	
	def __del__(self): #Destructor
		print "hope you learnt something, bye"
		del self

class B:
  #dummy class, nothing big here
	intAttribute = 1	

  #Inherited class. Python allows multiple inheritance
class C (A,B):
	intAttribute = 2
	
	def printIntAttribute(self):
		print "A's intAttribute value {}".format(A.intAttribute) #accessing hidden attributes
		print "B's intAttribute value {}".format(B.intAttribute)
		print "C's intAttribute value {}".format(self.intAttribute)


if __name__ == '__main__':
	a = A()
	print "A's intAttribute: {}".format(a.intAttribute)
	print "A's charAttribute: {}".format(a.charAttribute)
	print "using the getter to access integer, it is: {}".format(a.getIntAttribute())
	a.setIntAttribute(6)
	print "Accessing the hidden attribute: "+a._A__hiddenAttribute
	'''
	NOTE
	a.setIntAttribute(a,5) Won't work
	 Will say  
		File "oop.py", line 24, in <module>
    		a.setIntAttribute(a,5)
		TypeError: setIntAttribute() takes exactly 2 arguments (3 given)

	 The self argument is sent implicitly and needn't be mentioned
	'''
	print "After changing the value: {}".format(a.getIntAttribute())
	c = C()
	c.printIntAttribute()