Containership is the concept of having one or more objects
of one or more classes as data members of another class. Containership is the capacity of a class to contain
objects of different classes as member’s data. For example, the class A could contain an object of class B
as a member. Here, all public functions defined in B can be used in the class
A. The Class A becomes the container, while the class B becomes the contained
class. In OOP, Containership represents one ‘has – a’ relation. It is important
to note that, although the container has access to carry out all public methods
of the contained class, it is not able to change or provide additional
functionality.
Inheritance is the capacity for a class to inherit properties and
behavior of a parental class by spreading it. Inheritance principally provides
code reuse by allowing extending properties and behavior of an existing class
by a newly defined class. If the class A is created from Class B, therefore the
class B is parent class and the class A is called the child class (or derived
class/sub class). The behavior of
parent class can be overridden by derived class i.e. a derive class can modify
the functions of parent class in it.
Difference between Containership and Inheritance:
If a
class is extended, it inherits all public and protected properties/ behaviours and these behaviours can
be overridden by the subclass. But if a class is contained in other one, the
container does not get the capacity to change or add behavior to the contained
class i.e. container. In Inheritance, the
behavior of parent class can be overridden by derived class i.e. a derive class
can modify the functions of parent class in it.
Inheritance
represents ‘is -a ‘relationship in OOP, while Containership represents a’ has
-a’ relationship.
