As an object oriented programming language python stresses on objects. Classes are the blueprint from which the objects are created. Each class in python can have many attributes including a function as an attribute.
Accessing the attributes of a class
To check the attributes of a class and also to manipulate those attributes, we use many python in-built methods as shown below.
getattr() − A python method used to access the attribute of a class.
hasattr() − A python method used to verify the presence of an attribute in a class.
setattr() − A python method used to set an additional attribute in a class.
The below program illustrates the use of the above methods to access class attributes in python.
Example
class StateInfo:
StateName='Telangana'
population='3.5 crore'
def func1(self):
print("Hello from my function")
print getattr(StateInfo,'StateName')
# returns true if object has attribute
print hasattr(StateInfo,'population')
setattr(StateInfo,'ForestCover',39)
print getattr(StateInfo,'ForestCover')
print hasattr(StateInfo,'func1')Output
Running the above code gives us the following result −
Telangana True 39 True
Accessing the method of a class
To access the method of a class, we need to instantiate a class into an object. Then we can access the method as an instance method of the class as shown in the program below. Here through the self parameter, instance methods can access attributes and other methods on the same object.
Example
class StateInfo:
StateName='Telangana'
population='3.5 crore'
def func1(self):
print("Hello from my function")
print getattr(StateInfo,'StateName')
# returns true if object has attribute
print hasattr(StateInfo,'population')
setattr(StateInfo,'ForestCover',39)
print getattr(StateInfo,'ForestCover')
print hasattr(StateInfo,'func1')
obj = StateInfo()
obj.func1()Output
Running the above code gives us the following result −
Telangana True 39 True Hello from my function
Accessing the method of one class from another
To access the method of one class from another class, we need to pass an instance of the called class to the calling class. The below example shows how it is done.
Example
class ClassOne: def m_class1(self): print "Method in class 1" # Definign the calling Class class ClassTwo(object): def __init__(self, c1): self.c1 = c1 # The calling method def m_class2(self): Object_inst = self.c1() Object_inst.m_class1() # Passing classone object as an argument to classTwo obj = ClassTwo(ClassOne) obj.m_class2()
Output
Running the above code gives us the following result −
Method in class 1