Alloy Design Patterns

Abstract factory

Provide an interface for creating families of related or dependent objects without specifying their concrete classes

Builder

Separate the construction of a complex object from its representation so that the same construction process can create different representations

Factory Method

Define an interface for creating an object, but let subclasses decide which class to instantiate. Factory Method lets a class defer instantiation to subclasses

Prototype

Specify the kinds of objects to create using a prototypical instance, and create new objects by copying this prototype

Singleton

Ensure a class only has one instance, and provide a global point of access to it

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Adapter

Convert the interface of a class into another interface clients expect. Adapter lets classes work together that couldn't otherwise because of incompatible interfaces

Bridge

Decouple an abstraction from its implementation so that the two can vary independently

Composite

Compose objects into tree structures to represent part-whole hierarchies. Composite lets clients treat individual objects and compositions of objects uniformly

Decorator

Attach additional responsibilities to an object dynamically. Decorators provide a flexible alternative to subclassing for extending functionality

Façade

Provide a unified interface to a set of interfaces in a subsystem. Facade defines a higher-level interface that makes the subsystem easier to use

Flyweight

Use sharing to support large numbers of fine-graned objects efficiently

Proxy

Provide a surrogate or placeholder for another object to control access to it

Repository

The abstraction of data storage to allow for multiple different implementations where only one is selected but not known about by the repository user

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Chain of responsibility

Avoid coupling the sender of a request to its receiver by giving more than one object a chance to handle the request. Chain the receiving objects and pass the request along the chain until an object handles it

Command

Encapsulate a request as an object, thereby letting you parameterize clients with different requests, queue or log requests, and support undo-able operations

Interpreter

Given a language, define a representation for its grammar along with an interpreter that uses the representation to interpret sentences in the language

Iterator

Provide a way to access the elements of an aggregate object sequentially without exposing its underlying representation

Mediator

Define an object that encapsulates how a set of objects interact. Mediator promotes loose coupling by keeping objects from referring to each other explicitly, and it lets you vary their interaction independently

Memento

Without violating encapsulation, capture and externalize an object's internal state so that the object can be restored to this state later

Observer

Define a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically

State

Allow an object to alter its behavior when its internal state changes. The object will appear to change its class

Strategy

Define a family of algorithms, encapsulate each one, and make them interchangeable. Strategy lets the algorithm vary independently from clients that use it

Template method

Define the skeleton of an algorithm in a operation, deferring some steps to subclasses. Template Method lets subclasses redefine certain steps of an algorithm without changing the algorithm's structure

Visitor

Represent an operation to be performed on the elements of an object structure. Visitor lets you define a new operation without changing the classes of the elements on which it operates

Unit of work

This is a class that is responsible for keeping running modifications to commit to a repository in memory. When ready, the unit of work can be committed all in a single transaction. A unit of work can be thought of as a ledger/transaction for work done by a single request

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Read more on wikipedia or by buying the book by the gang of four Design Patterns: Elements of Reusable Object-Oriented Software