Software Design Patterns

Software Design Patterns

• Creational patterns:
  • Singleton: ensures a class has only one instance
  • Factory: provides a way to create objects without specifying the exact class of object
  • Abstract Factory: provides a way to create families of related objects
• Structural patterns:
  • Adapter: allows incompatible objects to work together
  • Bridge: separates an object's abstraction from its implementation
  • Composite: allows clients to treat individual objects and compositions of objects uniformly
• Behavioral patterns:
  • Observer: defines a one-to-many dependency between objects
  • Strategy: defines a family of algorithms, encapsulates each one, and makes them interchangeable
  • Template Method: defines the skeleton of an algorithm, allowing subclasses to fill in the details

Testing and Debugging

• Types of testing:
  • Unit testing: tests individual units of code
  • Integration testing: tests how units of code work together
  • System testing: tests the entire system
  • Acceptance testing: tests if the system meets the requirements
• Debugging techniques:
  • Print statements: adds print statements to identify the point of failure
  • Breakpoints: pauses the execution of the program at a specific point
  • Logging: records events and errors during the execution of the program

Object-Oriented Programming

• Key concepts:
  • Encapsulation: hides internal implementation details from the outside world
  • Abstraction: shows only necessary information to the outside world
  • Inheritance: creates a new class based on an existing class
  • Polymorphism: allows objects of different classes to be treated as objects of a common superclass
  • Composition: an object is composed of other objects or collections of objects

Requirements Analysis and Specification

• Requirements gathering:
  • Interviews: one-on-one or group discussions with stakeholders
  • Surveys: written or online questionnaires
  • Observation: observing users in their natural environment
  • Prototyping: creating a mock-up or a working model
• Requirements specification:
  • Functional requirements: describes what the system must do
  • Non-functional requirements: describes how the system should perform
  • User interface requirements: describes how the system should interact with the user

Coding and Documentation

• Coding principles:
  • Don't Repeat Yourself (DRY): avoids duplication of code
  • Keep It Simple, Stupid (KISS): favors simplicity over complexity
  • Single responsibility principle (SRP): a class should have only one reason to change
• Documentation:
  • Code comments: explains the purpose and functionality of the code
  • API documentation: describes the usage and parameters of functions and classes
  • User documentation: provides instructions and guides for users

Software Design Patterns

• Singleton pattern ensures a class has only one instance, controlling object creation.
• Factory pattern provides a way to create objects without specifying the exact class of object, promoting flexibility.
• Abstract Factory pattern creates families of related objects, providing a way to encapsulate a group of individual factories.

Testing and Debugging

• Unit testing involves testing individual units of code, focusing on specific components.
• Integration testing examines how units of code work together, ensuring seamless interactions.
• System testing evaluates the entire system, verifying its functionality as a whole.
• Acceptance testing determines if the system meets the requirements, ensuring it meets user needs.
• Debugging techniques include print statements, adding temporary output to identify the point of failure.
• Breakpoints pause the execution of the program at a specific point, allowing for inspection.
• Logging records events and errors during the execution of the program, providing a trail of system activity.

Object-Oriented Programming

• Encapsulation hides internal implementation details from the outside world, protecting sensitive information.
• Abstraction shows only necessary information to the outside world, simplifying complex systems.
• Inheritance creates a new class based on an existing class, promoting code reuse and a hierarchical relationship.
• Polymorphism allows objects of different classes to be treated as objects of a common superclass, increasing flexibility.
• Composition enables an object to be composed of other objects or collections of objects, forming complex structures.

Requirements Analysis and Specification

• Requirements gathering involves interviews, one-on-one or group discussions with stakeholders to gather information.
• Surveys use written or online questionnaires to collect data from a larger audience.
• Observation involves observing users in their natural environment, providing insights into real-world usage.
• Prototyping creates a mock-up or a working model, allowing for early testing and feedback.
• Functional requirements describe what the system must do, outlining its core functionality.
• Non-functional requirements describe how the system should perform, including aspects like speed and security.
• User interface requirements outline how the system should interact with the user, ensuring an intuitive experience.

Coding and Documentation

• The Don't Repeat Yourself (DRY) principle avoids duplication of code, reducing maintenance and improving efficiency.
• The Keep It Simple, Stupid (KISS) principle favors simplicity over complexity, making code easier to understand and maintain.
• The Single responsibility principle (SRP) states that a class should have only one reason to change, promoting modularity and flexibility.
• Code comments explain the purpose and functionality of the code, providing context for developers.
• API documentation describes the usage and parameters of functions and classes, acting as a reference for developers.
• User documentation provides instructions and guides for users, ensuring a smooth and efficient experience.