The document discusses the usefulness of dependency injection for software design. It notes that dependency injection helps achieve goals like maintainability, testability, flexibility, and loose coupling between components. Specific benefits mentioned include the ability to replace parts without recompiling, facilitating parallel development so independently developed components work together, and managing cross-cutting concerns like validation and logging. The document also lists some relevant software development principles like the SOLID principles and mentions the dependency injection principle.

1. Dependency
Injection
July 12, 2013
© TalentSoft – Deep Dives – Dependency Injection – Julien PLEE

2. Usefulness of
Dependency Injection
“It is very hard to make existing systems more maintainable. It is
much better to design for maintainability from the very start.”
• Therefore, Maintainability is one of our design goals
• Testability: TDD forces the design to be testable, reduce
likelihood of regressions, and make refactoring easier. +
Test Doubles.
• Flexibility and extensibility: always remember
business requirements often change.
© TalentSoft – Deep Dives – Dependency Injection – Julien PLEE

3. Usefulness of
Dependency Injection
• Late Binding is the ability to replace part of our system
without recompiling (e.g.: plug-in architecture)
• Parallel Development: Managing multiple groups to
ensure independently developed component will work
together
• Crosscutting concerns: Validation, Exception Handling,
Logging…
© TalentSoft – Deep Dives – Dependency Injection – Julien PLEE

4. Usefulness of
Dependency Injection
“Loose coupling should be a general design goal for your
enterprise applications.”
• Loose Coupling, as opposed to Tight Coupling, means
reducing the number of dependencies between
components of your system.
© TalentSoft – Deep Dives – Dependency Injection – Julien PLEE

5. Software Development
Principles
• SOLID
o Single Responsibility Principle
o Open Closed Principle
o Liskov Substitution Principle
o Interface Segregation Principle
o Dependency Injection Principle
© TalentSoft – Deep Dives – Dependency Injection – Julien PLEE