Data Abstraction

Unity of a program in modularity

Functions, data structures, modules

interface in modularity

Types and operations defined in a component that are visible outside it

specification

describes the intended functionality of a component as observed through the interface

implementation

data structures and functions inside the component not necessarily visible from outside

data type defining in abstraction

by its values and the operations that can be performed on it

what is hidden in data abstraction

the representation of the data and operations (encapsulation)

what does control abstraction do

hides implementation details of procedure bodies

what does data abstraction do

hides how data structures are represented and how operations are implemented

example of implementation hiding

A priority queue implemented as a binary search tree, a partially ordered vector

purpose of linguistic support in abstraction

to enforce information hiding at the language level

core idea of ADTs

separate the interface from the implementation

Example: A set with operations like empty, union, insert, is_member implemented using vectors or lists

type checking

ensures interface/implementation separation together with encapsulation

ADT for a stack of int

includes operations like push , pop, empty, and internal management of the stack structure

representation-independent

the user cannot distinguish between different correct implementations of the same abstract type

encapsulation

the implementation can be changed without affecting users of the component

use of modules

Information hiding and organizing code. 2 parts of a module: Interface: names and types exposed to the user, Implementation: declarations and internal details. Examples: in ML: Structures, in Ada: packages