Architecture Principles

Instructions

Apply 3 principles

SSOT (Single Source of Truth): One place for each constant or logic DRY (Don't Repeat Yourself): Extract when repeated 2+ times Anti-Spaghetti: Clear layers, minimal dependencies

When to apply

Planning: Design with SSOT in mind Implementing: Extract shared logic Reviewing: Check for duplication

Example

Python Example

# ❌ Duplicated
def validate_api(value):
    if value < 10.0: raise ValueError("Too low")

def validate_webhook(value):
    if value < 10.0: raise ValueError("Too low")

# ✅ SSOT + DRY
class Validator:
    MIN_VALUE = 10.0  # SSOT: Single source

    def validate_value(self, value):  # DRY: Reusable
        if value < self.MIN_VALUE:
            raise ValueError(f"Below {self.MIN_VALUE}")

# Anti-Spaghetti: Use everywhere
validator.validate_value(value)

JavaScript/Node.js Example

// ❌ Duplicated
function validateApi(value) {
    if (value < 10.0) throw new Error("Too low");
}

function validateWebhook(value) {
    if (value < 10.0) throw new Error("Too low");
}

// ✅ SSOT + DRY
class Validator {
    static MIN_VALUE = 10.0;  // SSOT: Single source

    validateValue(value) {  // DRY: Reusable
        if (value < Validator.MIN_VALUE) {
            throw new Error(`Below ${Validator.MIN_VALUE}`);
        }
    }
}

// Anti-Spaghetti: Use everywhere
const validator = new Validator();
validator.validateValue(value);

Go Example

// ❌ Duplicated
func validateApi(value float64) error {
    if value < 10.0 { return errors.New("Too low") }
    return nil
}

func validateWebhook(value float64) error {
    if value < 10.0 { return errors.New("Too low") }
    return nil
}

// ✅ SSOT + DRY
type Validator struct {
    MinValue float64  // SSOT: Single source
}

func NewValidator() *Validator {
    return &Validator{MinValue: 10.0}
}

func (v *Validator) ValidateValue(value float64) error {  // DRY: Reusable
    if value < v.MinValue {
        return fmt.Errorf("Below %.2f", v.MinValue)
    }
    return nil
}

// Anti-Spaghetti: Use everywhere
validator := NewValidator()
validator.ValidateValue(value)

Checklist

[ ] Constants in one place (SSOT)?
[ ] Repeated logic extracted (DRY)?
[ ] Clear layer separation (Anti-Spaghetti)?

For detailed patterns, see reference.md For more examples, see examples.md