Defining and using class variables

prahate · prahate · commit 0ac15575df17 · 2018-11-23T12:55:12.000+05:30
diff --git a/python_classes2.py b/python_classes2.py
@@ -0,0 +1,49 @@
+# self is defined as an instance of a class(similar to this in c++),and variables e.g. first, last and pay are called instance variables.
+# instance variables are the ones that are unique for each instance e.g. first, last and pay. They are unique to each instance.
+# __init__ is called as constructor(in languages like c++), this function is called as soon as we create object/instance of the class.
+# we can pass default values to functions as __init__(self, pay=3000)
+
+# we are going to use class variables 
+# class variables are the ones that are common to instance or in other words varibales that can be shared between the instances
+
+
+class Employee:
+
+	raise_amount = 1.04 # is a class variable 
+
+	def __init__(self, first, last, pay):
+		self.first = first
+		self.last = last
+		self.pay = pay
+
+	def full_name(self):
+		return '{} {}'.format(self.first, self.last)
+
+	def apply_raise(self):
+		self.pay = int(self.pay * self.raise_amount)
+		# other way to use class variables is using class name as shown below
+		# self.pay = int(self.pay * Employee.raise_amount)
+		# Both ways of using class variables is valid. the difference in them is
+		# self.raise_amount will be valid for particular instance meaning that we can set raise_amount to different value for
+		# particular instance by using e1.raise_amount = 1.05 and then if we print raise_amount for both of our instances
+		# we can find that raise_amount will be 1.05 for e1 but for e2 it will still be 1.04
+
+# below e1 and e2 are called instances of class employee
+e1 = Employee('sheldon', 'cooper', 5000)
+e2 = Employee('Prathamesh', 'rahate', 6000)
+
+#illustrating use of using self.raise_amount in apply_raise method
+e1.raise_amount = 1.05
+
+print(e1.raise_amount)
+print(e2.raise_amount)
+
+e1.apply_raise()
+e2.apply_raise()
+
+print(e1.pay)
+print(e2.pay)
+
+#to print instance of class like what it contains
+print(e1.__dict__)
+print(e2.__dict__)
