Tuesday, 10 November 2020

Object interface design - telling it to do something vs doing something to it

 An object represents a concept otherwise known as a "thing" or noun. Traditionally, we're taught that you can create an object then tell it what to do, however, this design (coming from Alan Kay) actually results in a mess of global state (which is the usual complaint about OOP). A more appropriate view is a little more complicated, we can create an object but we must define what we can do TO it.

For example you can Squeeze an Orange, therefore the object Orange has the Squeeze method. Traditionally it would be modelled as Person.Squeeze(Orange) however, here you aren't actually doing something TO the person object you are telling the person to do SOMETHING.

No comments:

Post a comment

Abstraction function, representation invariant

Abstraction Function & Rep invariant The abstraction functions map values in a class to the abstract concept's required values. The ...