Observer Pattern

This diagram illustrates the relationships between the Observer interface, the Subject class, and the concrete observer classes SendMailObserver and LogMailObserver. The Subject class maintains a list of observers and notifies them of state changes, while the concrete observer classes implement the update method to perform specific actions when notified.

Strategy Pattern

This diagram represents the relationships between the Logger interface, the LogContext class, the concrete DbLogger and FileLogger classes, and the Module class that uses the LogContext to log information using different strategies.

Object Adapter Pattern

This diagram represents the relationships between the Database interface, the Client class, the PostgresqlDatabase interface, the PostgresqlClient class, the ClientAdapter class that adapts PostgresqlClient to Database, and the Module class that uses either a Client or a ClientAdapter to perform actions.