Definition
Reusable program components are blocks of code (functions, classes, subroutines) designed to be used in multiple programs or different parts of the same program. They are key to efficient software development.
Advantages of Reusable Components
Key Point
| Advantage of reuse | Practical effect |
|---|---|
| Time/cost efficiency | Faster development with less duplicated work |
| Reliability | Reused components are often already tested |
| Consistency | Same behaviour across multiple modules/projects |
| Maintainability | One fix can improve all places where component is used |
Challenges
Key Point
| Reuse challenge | Practical impact |
|---|---|
| Compatibility issues | Integration can fail across different environments/frameworks |
| Modification costs | Adapting third-party code may be expensive/complex |
| Learning curve | Team needs time and documentation to use components correctly |
Worked Example
Worked Example: Reusable Sorting Component
Benefit: The quickSort function is written once, tested thoroughly, and reused across multiple programs without rewriting or retesting.
pseudocode
// Reusable sorting function in a library
function quickSort(array, compareFunction):
// Implementation of quicksort algorithm
// Thoroughly tested and optimised
end function
// Used in Program A: Sorting student grades
grades = [85, 92, 78, 95, 88]
sortedGrades = quickSort(grades, descending)
// Used in Program B: Sorting customer names
customers = ["Smith", "Jones", "Brown", "Taylor"]
sortedCustomers = quickSort(customers, alphabetical)
// Used in Program C: Sorting products by price
products = [{name: "Book", price: 10}, {name: "Pen", price: 2}]
sortedProducts = quickSort(products, byPrice)
Exam Tip
Exam Tips for Thinking Ahead:
• Be able to identify inputs and outputs for given scenarios
• Understand the purpose of preconditions and why they matter
• Explain benefits AND drawbacks of caching (don't just list benefits)
• Describe advantages and challenges of reusable components
• Give specific examples for each concept (ATM, stack, web browser, sorting)
• Consider data types appropriate for different inputs
• Be able to identify inputs and outputs for given scenarios
• Understand the purpose of preconditions and why they matter
• Explain benefits AND drawbacks of caching (don't just list benefits)
• Describe advantages and challenges of reusable components
• Give specific examples for each concept (ATM, stack, web browser, sorting)
• Consider data types appropriate for different inputs