This unit focuses on two design patterns: Observer and Strategy. We'll use these patterns to enable responsive security and flexible climate control in our smart home system.

1. Observer Pattern:

   • Purpose: Allows an object (observer) to watch another (subject) and get notified of changes.
   • Steps:
     • Define a Subject with registration, unregistration, and notification methods (e.g., for a SecuritySystem).
     • Implement observers that react to changes (e.g., SecurityApp, SecurityLight).

2. Strategy Pattern:

   • Purpose: Defines a family of algorithms and makes them interchangeable.
   • Steps:
     • Define a strategy interface with a method for the desired behavior (e.g., TemperatureControlStrategy for controlling temperature).
     • Implement specific strategies with concrete behavior (e.g., HeatingStrategy, CoolingStrategy).
     • Create a context to use and switch strategies (e.g., a ClimateControl system).

Here is the complete code to implement the Observer pattern:

The security_system instance notifies both SecurityApp and SecurityLight when the state changes to "Intrusion Detected".

Here is the complete code to implement the Strategy pattern:

The ClimateControl instance can switch between HeatingStrategy and CoolingStrategy to control the temperature accordingly.

By using the Observer and Strategy patterns, we enhance our smart home system's adaptability and functionality, allowing for responsive security alerts and flexible climate control.