Objects Are Not Abstract Data Types

#1

Post by liebke » Mon, Dec 14, 2009, 7:45 PM UTC

Objects Are Not Abstract Data Types
stuartsierra.com

Re: Objects Are Not Abstract Data Types

#2

Post by scott_s » Mon, Dec 14, 2009, 8:36 PM UTC

Also see "On Understanding Data Abstractions, Revisted": http://news.ycombinator.com/item?id=917065

Re: Objects Are Not Abstract Data Types

#3

Post by [deleted] » Mon, Dec 14, 2009, 8:38 PM UTC

[deleted]

Re: Objects Are Not Abstract Data Types

#4

Post by Kaizyn » Mon, Dec 14, 2009, 9:23 PM UTC

Objects aren't abstract data types because an object contains all of the methods to operate on the ADT in the same place.

Re: Objects Are Not Abstract Data Types

#5

Post by keefe » Mon, Dec 14, 2009, 9:31 PM UTC

my understanding is an object is a particular piece of memory, structured according to a class which may be seen as the abstract data type for that particular piece of data. As far as I understand the JVM, the compiler doesn't replicate function bodies for every instance of a class. I think a more appropriate title to this article would be... "protocols and datatypes in clojure", of course I wouldn't have read the article if that were the title...

Re: Objects Are Not Abstract Data Types

#6

Post by kqr2 » Mon, Dec 14, 2009, 9:59 PM UTC

Here's the CLU language home page:

http://www.pmg.lcs.mit.edu/CLU.html

Re: Objects Are Not Abstract Data Types

#7

Post by BigZaphod » Mon, Dec 14, 2009, 10:58 PM UTC

I might be wrong, but doesn't this describe Google Go's interfaces as well? As in, the data structure of an object is independent of the functions/methods that can operate on the object. At least that's how I understand it right now (having never used it). And the type of a thing is related to the set of functions (matched by name) that are expected to work rather than the data's memory structure.

Re: Objects Are Not Abstract Data Types

#8

Post by Miky » Mon, Dec 14, 2009, 11:37 PM UTC

What Clojure's getting reminds me of Haskell.

Re: Objects Are Not Abstract Data Types

#9

Post by cstejerean » Tue, Dec 15, 2009, 12:17 AM UTC

keefe wrote: post #5

my understanding is an object is a particular piece of memory, structured according to a class which may be seen as the abstract data type for that particular piece of data. As far as I understand the JVM, the compiler doesn't replicate function bodies for every instance of a class. I think a more appropriate title to this article would be... "protocols and datatypes in clojure", of course I wouldn't have read the ar…

"an object is a particular piece of memory, structured according to a class" does not sound like a particularly useful way to think about objects unless you are working at a low enough level that you care how objects are laid out in memory.

Re: Objects Are Not Abstract Data Types

#10

Post by tumult » Tue, Dec 15, 2009, 2:08 AM UTC

BigZaphod wrote: post #7

I might be wrong, but doesn't this describe Google Go's interfaces as well? As in, the data structure of an object is independent of the functions/methods that can operate on the object. At least that's how I understand it right now (having never used it). And the type of a thing is related to the set of functions (matched by name) that are expected to work rather than the data's memory structure.