Ruby single-state method analysis

The behavior of an object depends on its class, but we often know that a specific object requires a specific behavior. in many languages, we have to get into the trouble of defining another class, even if it is only used for the next ing. in Ruby, we can assign any object a method of its own.

Ruby> class SingletonTest
| Def size
| Print "25 \ n"
| End
| End
Nil
Ruby> test1 = SingletonTest. new
# <SingletonTest: 0xbc468>
Ruby> test2 = SingletonTest. new
# <SingletonTest: 0xbae20>
Ruby> def test2.size
| Print "10 \ n"
| End
Nil
Ruby> test1.size
25
Nil
Ruby> test2.size
10
Nil


In this example, test1 and test2 belong to the same class, but test2 has been assigned to an overloaded size method, so they have different behaviors. a method that only belongs to an object is called a single-state method.

The single-state method is often used for the design of graphical user interface (GUI) elements, where different buttons are pressed to stimulate different events.

The single-state method is not Ruby's patent. It also appears in CLOS, Dylan, and other languages. at the same time, some languages, such as Self and NewtonScript, have only single-State methods. they are sometimes called prototype-based languages.