In the Observer pattern, what does the 'subject' object do?
Provides an interface for attaching and detaching observer objects.
Observes the state of other objects.
Maintains a list of its dependents and notifies them of state changes.
Both B and C
What is a key characteristic of a well-implemented design pattern?
It promotes code reusability and maintainability.
It is tightly coupled to a specific problem domain.
It introduces significant code complexity.
It eliminates the need for documentation.
What is a potential drawback of using the Adapter Pattern?
It is not suitable for adapting interfaces with many methods.
It violates the Open/Closed Principle.
It can make the code more complex, especially with multiple adapters.
It can lead to performance issues due to the overhead of adaptation.
When might the Adapter Pattern be a suitable solution?
When you want to decouple your code from a specific third-party library.
When you want to define a template for creating objects.
When you need to create a new class with similar functionality to an existing one.
When you need to represent a hierarchical relationship between objects.
What is a key consideration when implementing the Singleton pattern in a multi-threaded application?
Using global variables to store the Singleton instance.
Creating separate instances for each thread.
Ensuring that only one instance can be created, even under concurrent access.
Avoiding any form of synchronization to improve performance.
Which of these is a common use case for the Observer pattern?
Defining a factory for creating objects.
Implementing a notification system.
Implementing an undo/redo mechanism.
Creating a singleton object.
What is a key benefit of encapsulating a request as an object in the Command Pattern?
It allows for requests to be queued, logged, or supported by other operations.
It prevents the use of undo/redo functionality.
It increases code coupling for better maintainability.
It makes the code more difficult to extend with new commands.
How does the Facade Pattern differ from an Adapter Pattern?
Facade changes the interface of a class, while Adapter adapts to a different one.
Facade focuses on simplifying interfaces, while Adapter deals with incompatible ones.
Facade creates a new interface, while Adapter unifies existing ones.
Both patterns have the same purpose and implementation, with no significant difference.
In the Adapter Pattern, what is the 'Adaptee'?
The client code that interacts with the adapter.
The class that implements the Adapter Pattern.
The class that needs to be adapted to a different interface.
The interface that the client expects to use.
In the Observer pattern, how are observers typically notified of changes?
By directly accessing the subject's state variables.
Through a method call on the observer object.
By sending an email notification.
Using a message queue.