Design Patterns Reloaded

Implementation of some design patterns in Java 17, some of them are from the GoF, others are the one you usually see in programs.

Like most of the GoF patterns, the implementations use delegation instead of inheritance, but also emphasis immutability when necessary.

abstract factory abstracts access to several factories
adapter to see an object from one interface as one from another interface
builder constructs objects by name instead of by position
chain of responsibility constructs a pipeline of objects that handle a request
command, objects that are actions
decorator dynamically adds behavior to an existing object
factory abstracts the creation of objects
memoizer caches the result of a computation to avoid multiple re-computations of the same value
monad wraps multiple disjoint states under a common API
observer de-couples codes by pushing the values from an object to another one
proxy see decorator
singleton see abstract-factory
railwayswitch abstracts a cascade of if ... else
state delegates API implementation to an internal state object
template_method define a behavior with a generic part and a specific part
typing, 3 kinds of relations between a static type and a runtime class
visitor, specify operations on a hierarchy of types outside that hierarchy

Old materials

I've done a presentation in English at Devoxx 2015

NB: A port exists in Scala