Don’t use flags as function parameters

Usage

📝 Guideline

Don't Use Flags as Function Parameters: Functions should have a single responsibility and flags indicate that a function does more than one thing.

Flags are often used as function parameters to control the behavior of a function. However, this practice can make the code harder to understand and maintain. Instead, it is recommended to split the function into multiple smaller functions, each with a clear and single purpose.

🛠️ How to Apply

• Split functions with flags into separate functions or methods, each responsible for a single task. 🚀
• Refactor the code to remove conditional statements based on flags and replace them with calls to the appropriate functions. 🔄
• Ensure that each function or method has a clear and well-defined responsibility. 🎯

Pros and Cons

👍 Pros

• Improved Readability: Functions with clear and single responsibilities are easier to understand, reducing cognitive load. 📖
• Enhanced Maintainability: Smaller, focused functions are easier to test, debug, and modify when needed. 🛠️
• Modularity: By splitting functions based on different tasks, code becomes more modular, promoting code reuse. 🧩

👎 Cons

• Increased Function Count: Splitting functions may result in an increase in the number of functions, which can make the codebase larger. 📈
• Potential Overhead: In some cases, creating multiple functions instead of using flags might introduce slight overhead due to function call overhead. ⏱️
• Code Duplication: Splitting functions without proper abstraction can lead to code duplication, which may introduce bugs and maintenance issues. 🐞

Examples

❌ Bad

// Bad: Using a flag to determine the behavior of the function
function drawShape(shape: string, fill: boolean) {
  if (fill) {
    // Draw filled shape
    console.log(`Drawing a filled ${shape}`)
  } else {
    // Draw outline only
    console.log(`Drawing an outlined ${shape}`)
  }
}
 
// Usage
drawShape('circle', true) // Draw a filled circle
drawShape('rectangle', false) // Draw an outlined rectangle

✅ Good

// Good: Separate functions for each shape drawing task
function drawFilledShape(shape: string) {
  console.log(`Drawing a filled ${shape}`)
}
 
function drawOutlinedShape(shape: string) {
  console.log(`Drawing an outlined ${shape}`)
}
 
// Usage
drawFilledShape('circle') // Draw a filled circle
drawOutlinedShape('rectangle') // Draw an outlined rectangle

References

🔀 Related Principles

• Single Responsibility Principle: Functions should have a single responsibility, which aligns with not using flags as function parameters. 🎯
• Code Reusability: By splitting functions, code becomes more modular and can be reused in different contexts. 🔄
• Separation of Concerns: Divide functions into smaller functions, each handling a specific concern. 📦