Strategy Pattern V/S Decorator Pattern

Question

I just came across two patterns.

1. Strategy Pattern

2. Decorator

Strategy Pattern :-

Strategy pattern

Answer 1

Strategy_pattern

1. Defines a family of algorithms,
2. Encapsulates each algorithm, and
3. Makes the algorithms interchangeable within that family.

Use Strategy pattern when you have to change algorithm dynamically at run time.

Decorator

Decorator pattern dynamically changes the functionality of an object at runtime without impacting the existing functionality of the objects.

When to use:

1. Add additional functionalities/responsibilities dynamically
2. Remove functionalities/responsibilities dynamically
3. Avoid too much of sub-classing to add additional responsibilities.

Drawbacks:

1. Overuse of Open Closed principle ( Open for extension and Closed for modification). Use this feature sparingly where the code is least likely changed.
2. Too many small classes and will add maintenance overhead.

Key difference:

Strategy lets you change the guts of an object. Decorator lets you change the skin.

Few more useful posts:

When to Use the Decorator Pattern?

Real World Example of the Strategy Pattern

strategy by sourcemaking