2.1.1 Thinking Abstractly

• Abstraction

  • The process of removing excessive details to represent a problem of only its key features
  • A representation of reality
• Generalisation

  • Part of process of Abstraction
  • Grouping together items with similar features which are relevant to problem
• Need for Abstraction

  • Enables programmers to focus on important aspects of problem rather than the messy and unnecessary detail
  • Enables programmers to work on different aspects of problem
  • Enables programmers to use pre-built and built-in functions without concerning themselves with how they work
  • prevents program from getting too large
  • reduces time needed to be spent on the project
• Examples of Abstraction

  1. Variables
  2. Objects
  3. Layers
  4. Data models
  5. Data Structures
  6. Entity-relationship diagrams
• Abstraction vs Reality

  • in OOP, the objects are abstractions of real-world entities and the attributes and methods represent the real-world characteristics and actions
• Data Abstraction

  Using a data structure without being concerned of how it works
• Representational Abstraction:

  • analysing what is relevant to a given scenario and simplifying a problem based on this information
• Abstraction by Generalisation:

  • grouping together items with similarities that are relevant to the problem (ignoring different features that are irrelevant to the problem)
  • solving new problems based on previous problems which already have an existing solution - involves using an algorithm that solves a problem and adapting it so it can solve similar problems
• Data Abstraction

  • subcategory is abstraction where details about how data is being stored are hidden
  • as a result, programmers can make use of abstract data structures (stacks and queues) without knowing how the structures are implemented
• Procedural Abstraction:

  • programmers can push and pop items to and from a stack without having any knowledge about the code used
  • once a procedure has been coded it can be used as a black-box
• Devising an Abstract Model for a variety of situations:

  • can the problem be solved using a computer program?
  • if yes:
  • what are the key features of the problem?
  • how will it be used?
  • who will be using it?
  • what is the skill set of the target user group?
  • what features are required by target audience for the program?