Attributes of a class are function objects that define corresponding methods of its instances. They are used to implement access controls of the classes.
Attributes of a class can also be accessed using the following built-in methods and functions :
- getattr() – This function is used to access the attribute of object.
- hasattr() – This function is used to check if an attribute exist or not.
- setattr() – This function is used to set an attribute. If the attribute does not exist, then it would be created.
- delattr() – This function is used to delete an attribute. If you are accessing the attribute after deleting it raises error “class has no attribute”.
The following methods are explained with the example given below :
# Python code for accessing attributes of class class emp: name='Harsh' salary='25000' def show(self): print self.name print self.salary e1 = emp() # Use getattr instead of e1.name print getattr(e1,'name') # returns true if object has attribute print hasattr(e1,'name') # sets an attribute setattr(e1,'height',152) # returns the value of attribute name height print getattr(e1,'height') # delete the attribute delattr(emp,'salary')
Harsh True 152
Static methods : A static method is a method[member function] that don’t use argument self at all. To declare a static method, proceed it with the statement “@staticmethod”.
# Python code for accessing methods using static method class test: @staticmethod def square(x): test.result = x*x # object 1 for class t1=test() # object 2 for class t2 = test() t1.square(2) # printing result for square(2) print t1.result t2.square(3) # printing result for square(3) print t2.result # printing the last value of result as we declared the method static print t1.result
4 9 9
Accessing attributes and methods of one class in another class
Accessing attributes and methods of one class in another class is done by passing the object of one class to another.
Explained with the example given below :
# Python code for Accessing attributes and methods # of one class in another class class ClassA(): def __init__(self): self.var1 = 1 self.var2 = 2 def methodA(self): self.var1 = self.var1 + self.var2 return self.var1 class ClassB(ClassA): def __init__(self, class_a): self.var1 = class_a.var1 self.var2 = class_a.var2 object1 = ClassA() # updates the value of var1 summ = object1.methodA() # return the value of var1 print summ # passes object of classA object2 = ClassB(object1) # return the values carried by var1,var2 print object2.var1 print object2.var2
3 3 2
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