Behavioral Design Patterns in C++ - Shapes Example - III

The lecture discusses the implementation of the visitor pattern to add new operations to a shape hierarchy without using dynamic cost. It starts with the Render class and RTTI usage, then introduces the visitor pattern. The implementation involves adding an accept method in shape subclasses and creating a visitor hierarchy. The Render class is adapted as a visitor to draw shapes. The lecture concludes with generating a class diagram, highlighting the benefits of the visitor pattern in maintaining code without modifications.

What was the main limitation of using RTTI in the Render class?

• It made the code less readable.

• It increased the complexity of the code.

• It required additional memory allocation.

• It involved dynamic cost which the instructor wanted to avoid.

What is the purpose of the 'accept' method in the shape hierarchy?

• To render shapes on the screen.

• To allow shapes to accept a visitor object.

• To initialize the shape objects.

• To store shape attributes.

How does the visitor pattern help in adding new operations to the shape hierarchy?

• By modifying the existing shape classes.

• By using RTTI to determine shape types.

• By allowing new operations without changing existing code.

• By creating new shape classes for each operation.

What role does the Render class play in the visitor pattern implementation?

• It acts as a base class for all shapes.

• It serves as a visitor to draw shapes.

• It initializes the visitor hierarchy.

• It stores the attributes of shapes.

What is a key advantage of using the visitor pattern as mentioned in the lecture?

• It reduces the number of classes needed.

• It allows adding new operations without modifying existing code.

• It eliminates the need for any hierarchy.

• It simplifies the code structure significantly.