Learning Python Design Patterns - Second Edition

The Observer pattern – advantages and disadvantages

The Observer pattern provides you with the following advantages:

• It supports the principle of loose coupling between objects that interact with each other
• It allows sending data to other objects effectively without any change in the Subject or Observer classes
• Observers can be added/removed at any point in time

The following are the disadvantages of the Observer pattern:

• The Observer interface has to be implemented by ConcreteObserver, which involves inheritance. There is no option for composition, as the Observer interface can be instantiated.
• If not correctly implemented, the Observer can add complexity and lead to inadvertent performance issues.
• In software application, notifications can, at times, ...