Python call attribute by string

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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 :

1. getattr() – This function is used to access the attribute of object.
2. hasattr() – This function is used to check if an attribute exist or not.
3. setattr() – This function is used to set an attribute. If the attribute does not exist, then it would be created.
4. 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 :

class emp: 

    name='Harsh'

    salary='25000'

    def show(self): 

        print (self.name) 

        print (self.salary) 

e1 = emp() 

print (getattr(e1,'name')) 

print (hasattr(e1,'name')) 

setattr(e1,'height',152) 

print (getattr(e1,'height')) 

delattr(emp,'salary') 

Output :

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”.

class test: 

    @staticmethod

    def square(x): 

        test.result = x*x 

t1=test() 

t2 = test() 

t1.square(2) 

print (t1.result) 

t2.square(3) 

print (t2.result) 

print (t1.result) 

Output :

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 :

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() 

summ = object1.methodA() 

print (summ) 

object2 = ClassB(object1) 

print( object2.var1)

print (object2.var2) 

Output :

3
3
2