mcp-server-milvus python-calisthenics.instructions.md

Object Calisthenics Rules for Python

⚠️ Warning: This file contains the 9 original Object Calisthenics rules. No additional rules must be added, and none of these rules should be replaced or removed. Examples may be added later if needed.

Objective

This rule enforces the principles of Object Calisthenics to ensure clean, maintainable, and robust code in Python, primarily for business domain code.

Scope and Application

• Primary focus: Business domain classes (aggregates, entities, value objects, domain services)
• Secondary focus: Application layer services and use case handlers
• Exemptions:
  • DTOs (Data Transfer Objects)
  • API models/contracts
  • Configuration classes
  • Simple data containers without business logic
  • Infrastructure code where flexibility is needed

Key Principles

1. One Level of Indentation per Method:

• Keep methods simple and limit the level of indentation to one.

# Bad Example - multiple levels of indentation
def send_newsletter():
    for user in users:
        if user.is_active:
            # Do something
            mailer.send(user.email)

# Good Example - Extracted method to reduce indentation
def send_newsletter():
    for user in users:
        send_email(user)

def send_email(user):
    if user.is_active:
        mailer.send(user.email)

2. Don't Use the ELSE Keyword:

• Avoid using else to simplify control flow. Use early returns or fail fast.

# Bad Example - Using else
def process_order(order):
    if order.is_valid:
        # Process order
    else:
        # Handle invalid order

# Good Example - Avoiding else
def process_order(order):
    if not order.is_valid:
        return  # early return to handle invalid case
    # Process order

• Fail Fast principle example:

def process_order(order):
    if order is None:
        raise ValueError("Order cannot be None")
    if not order.is_valid:
        raise ValueError("Invalid order")
    # Process order