Question

Anyone know a list of design pattern only applicable to static typing language but not dynamic typing language?

E.g. strategy

Answer 1

There are two aspects to a design pattern: a partitioning of responsibilities in order to improve program structure, enable flexibility and ease maintenance. And a language-specific set of constructs to implement that pattern. In some cases we are supplementing the language’s natural capabilities with cunning design.

Strategy pattern is described here as

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

Now this design goal of decoupling clients from the specifics of implementation is surely applicable in dynamic languages as well as static languages.

The details vary because Static languages lead us to declare explicit Interfaces and code the clients to use interfaces while dynamic languages can use “Duck Typing” but coding to deal with receiving lions where ducks were expected. (animal->eat() … no no! not eat me!)

I’m expecting to see examples of most design patterns in dynamic code possibly represented rather differently – the same separations of concerns are still important.