Wednesday, July 23, 2003

Message Object Oriented vs Function Object Oriented. In a conversation in another forum, the question came up whether Smalltalk's messaging view of the interaction between objects has a correlary in the Static Typing world. Specifically, is the concept of capturing #doesNotUnderstand and doing creative dispatching something that's anathema to static type checking? The Message oriented languages (of which I know Smalltalk and Objective C) make objects act essentially like servers - when messaged they can simply handle the message, ignore the message, forward the message, or signal a fault. The messages themselves are available as a chunk of data to examine, or modify as necessary. Messages are sent to an object's handler ("method" if you like), or to #doesNotUnderstand: if no handler exists. What you want to do in there is your business but the default is to halt the process and slap a debugger around it... This mechanism makes possible a number of very powerful techniques that are simply beyond the ken of the average function calling language user. ...the message can be reified as data and manipulated, and the mapping between message and method is looser and can be something other than a simple name/signature mapping. [Lambda the Ultimate] 10:42:34 AM    comment []

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