dependency-inversion-principle
Dependency Inversion Principle (DIP)
Overview
High-level modules should not depend on low-level modules. Both should depend on abstractions.
Classes should depend on interfaces, not concrete implementations. Dependencies should be injected, not instantiated internally.
When to Use
- Creating any class that uses external services
- Class uses database, email, file system, APIs
- Writing
new ConcreteClass()inside another class - Told "don't overcomplicate with DI"
The Iron Rule
NEVER instantiate dependencies inside a class. Always inject them.
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54keep-it-simple
Use when tempted to write clever code. Use when solution feels complex. Use when showing off skills instead of solving problems.
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39fail-fast
Use when handling errors. Use when tempted to catch and swallow exceptions. Use when returning default values to hide failures.
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