Question

How will you facilitate data abstraction? Explain it with a suitable example?

Answer 1

The definition of ADT only mentions what operations are to be performed but not how these operations will be implemented. It does not specify how data will be organized in memory and what algorithms will be used for implementing the operations. It is called “abstract” because it gives an implementation-independent view. The process of providing only the essentials and hiding the details is known as abstraction.
To facilitate data abstraction, you will need to create two types of functions.

constructors and selectors:
Constructors are functions that build the abstract data type. Selectors are functions that retrieve information from the data type.
To create a city object, you’d use a function as a city = makecity (name, lat, Ion)
To extract the information of a city object, you would use functions like

1. getname(city)
2. getlat(city)
3. getlon(city)

In the above pseudo-code, the function which creates the object of the city is the constructor, city = makecity (name, lat, Ion)
Here makecity (name, lat, Ion) is the constructor which creates the object city.

constructor

Selectors are nothing but functions that retrieve information from the data type. Therefore in the above code

1. getname(city)
2. getlat(city)
3. getlon(city)

are the selectors because these functions extract the information of the city object.

Data abstraction is supported by defining an abstract data type (ADT), which is a collection of constructors and selectors. Constructors create an object, bundling together different pieces of information, while selectors extract individual pieces of information from the object.