What design patterns do you use in your work?

In my work, I regularly use the following design patterns:

• Creational:

  • Singleton: Ensures that a class has only one instance and provides a global point of access to it. Used for loggers, configuration settings.
  • Factory Method: Defines an interface for creating an object but allows subclasses to alter the type of objects that will be created. Used for creating objects whose type is determined at runtime or depends on the context.
  • Abstract Factory: Provides an interface for creating families of related or dependent objects without specifying their concrete classes. Used for creating sets of related objects, for example, for working with different databases.
  • Builder: Separates the construction of a complex object from its representation so that the same construction process can create different representations. Used when an object has many optional parameters.

• Structural:

  • Adapter: Converts the interface of a class into another interface clients expect. Allows classes with incompatible interfaces to work together.
  • Decorator: Dynamically adds new capabilities to an object by wrapping it. Used to extend the functionality of objects without changing their structure, for example, for logging or data compression in input/output streams.
  • Proxy: Provides a substitute or placeholder for another object to control access to it. Used for lazy initialization, access control, logging, or caching.
  • Facade: Provides a unified interface to a set of interfaces in a subsystem. Defines a higher-level interface that makes the subsystem easier to use.

• Behavioral:

  • Observer: Defines a one-to-many dependency between objects so that when one object changes its state, all its dependents are notified and updated automatically. Used for implementing event-driven models.
  • Strategy: Defines a family of algorithms, encapsulates each one, and makes them interchangeable. Allows clients to choose an algorithm at runtime. Used for providing different implementations of a task.
  • Template Method: Defines the skeleton of an algorithm in an operation, deferring some steps to subclasses. Allows subclasses to override certain steps of an algorithm without changing its structure.
  • Iterator: Provides a way to access the elements of a composite object sequentially without exposing its internal representation.
  • State: Allows an object to alter its behavior when its internal state changes. The object will appear as if it changed its class.

The choice of pattern depends on the specific task and context. Knowledge of these and other patterns helps create flexible, extensible, and maintainable code.