Replace Temp with Query

A local variable that stores an expression result can be replaced with a method — making the logic reusable and the code self-documenting.

When to Use

• A temp variable is assigned once, then only read (never reassigned)
• The expression is complex enough to deserve a name
• The value is needed in multiple methods of the class
• Preparing for Extract Method (temps inside a long method block extraction)

How to Apply

1. Ensure the temp is assigned exactly once and not modified afterward
2. Extract the right-hand side expression into a method
3. Replace the temp variable usages with calls to the new method
4. Remove the temp variable declaration
5. Run tests

Example

// Before
function getPrice(): number {
  const basePrice = quantity * itemPrice;
  const discount = basePrice > 1000 ? basePrice * 0.05 : 0;
  return basePrice - discount;
}

// After
function getPrice(): number {
  return basePrice() - discount();
}
function basePrice(): number { return this.quantity * this.itemPrice; }
function discount(): number { return this.basePrice() > 1000 ? this.basePrice() * 0.05 : 0; }

References

• refactoring.guru/replace-temp-with-query