10_classes_and_objects.py

"""
Module 10: Classes and Objects
Learn: class, __init__, self, methods

In the advanced courses, you'll use objects constantly:
    client = Anthropic()
    workflow = StateGraph(AgentState)
    response = client.messages.create(model=MODEL, ...)
Understanding classes helps you read SDK code confidently.
"""

# --- Basic class ---
class MenuItem:
    def __init__(self, name, price, category="main"):
        self.name = name
        self.price = price
        self.category = category

    def describe(self):
        return f"{self.name} (${self.price:.2f}) [{self.category}]"

# Create objects (instances)
burger = MenuItem("Mushroom Burger", 12.99)
bowl = MenuItem("Quinoa Power Bowl", 10.99, category="bowl")

print(burger.describe())
print(bowl.describe())
print(f"Burger price: {burger.price}")

# --- __str__ for nice printing ---
class AgentConfig:
    def __init__(self, role, model="gpt-4o-mini"):
        self.role = role
        self.model = model
        self.history = []

    def __str__(self):
        return f"Agent({self.role}, model={self.model})"

    def add_message(self, role, content):
        self.history.append({"role": role, "content": content})

    def message_count(self):
        return len(self.history)

agent = AgentConfig("SQL Expert")
print(f"\n{agent}")  # Uses __str__

agent.add_message("user", "How many orders?")
agent.add_message("assistant", "Let me check...")
print(f"Messages: {agent.message_count()}")

# --- Why this matters: SDK clients are just objects ---
# In the Claude Code agent:
#   client = Anthropic()                    ← creates an object
#   response = client.messages.create(...)  ← calls a method
#
# In the RAG workshop:
#   client = QdrantClient(":memory:")       ← creates an object
#   client.add(collection, documents)       ← calls a method

# --- @property for computed values ---
class Session:
    def __init__(self):
        self.events = []

    def add_event(self, event):
        self.events.append(event)

    @property
    def event_count(self):
        return len(self.events)  # No () needed when called

session = Session()
session.add_event("start")
session.add_event("query")
print(f"\nEvents: {session.event_count}")  # Looks like an attribute, acts like a method

# 🎯 Exercise: Create a Tool class with name, description, and a run() method