Combine Functions into Class

Removes smells

Referenced by patterns

Symptom

The agent finds multiple functions that all take the same data shape; reasoning about the data requires loading every operation that touches it scattered across files.

Goal

Operations live with the data they act on; the agent loads one class to reason about both shape and behavior.

Before the refactoring

function baseCharge(reading) {
  return reading.kwh * reading.tariff.baseRate;
}
function taxableCharge(reading) {
  return baseCharge(reading) + reading.kwh * reading.tariff.taxRate;
}

After the refactoring

class Reading {
  constructor({ kwh, tariff }) { this.kwh = kwh; this.tariff = tariff; }
  baseCharge()    { return this.kwh * this.tariff.baseRate; }
  taxableCharge() { return this.baseCharge() + this.kwh * this.tariff.taxRate; }
}

Example source: Illustrative example written for this site, not a quotation from any source.

Pressure

The agent traces operations across modules to understand what the data can do; invariants the agent must respect aren't enforced at construction.

Tradeoff

Wrapping the data in a class adds construction ceremony at every entry point; for data only used in one place the class is more code than the original concern warranted.

Relief

The agent loads the class as a single unit; behavior, fields, and invariants all in one place with one import.

Trap

Wrapping data that nobody else operates on creates a class the agent must instantiate everywhere with no encapsulation gain — pure overhead.