The 10 Most Important Software Design Patterns

Singleton pattern: This pattern ensures that a class has only one instance, and provides a global access point to it. The singleton class itself is responsible for creating and managing its own unique instance. This can be useful when a system requires a single instance of a class to coordinate actions across the system.

Factory pattern: This pattern creates objects without specifying the exact class to create. Instead, it relies on a factory object to create the objects based on a set of input parameters. This allows for a level of flexibility, as the factory object can be changed to create different types of objects depending on the needs of the system.

Abstract factory pattern: This pattern creates objects that belong to a super class, but the objects are created by child classes. This allows for the creation of objects that belong to a particular family, without specifying the exact type of object to create.

Builder pattern: This pattern separates object construction from its representation, allowing for the same construction process to create different representations. This can be useful when creating complex objects that require a lot of setup, as the builder pattern allows for this setup to be done in a more organized and readable way.

Prototype pattern: This pattern creates new objects by copying existing objects. This can be useful when the cost of creating a new object is expensive or time-consuming, and it is more efficient to create a copy of an existing object instead.

Adapter pattern: This pattern allows two incompatible interfaces to work together by wrapping one interface with an adapter. The adapter object translates requests from the first interface into a form that the second interface can understand. This can be useful when integrating two systems that were not originally designed to work together.

Bridge pattern: This pattern separates an abstraction from its implementation, allowing the two to vary independently. This can be useful when it is necessary to modify the implementation of a system without changing the interface that clients use to access it.

Filter pattern: This pattern filters a set of objects using a set of criteria. It can be useful for selecting a subset of objects based on specific properties, such as selecting all objects that are red in color.

Composite pattern: This pattern creates a tree structure of objects in which individual objects and compositions of objects all behave in the same way. This can be useful when it is necessary to treat individual objects and compositions of objects in the same way.

Decorator pattern: This pattern allows additional behavior to be added to an existing object dynamically, by wrapping the object in a decorator object. This can be useful when it is necessary to add new behavior to an existing object without altering its implementation.