BJO - information hiding v/s encapsulation

[ankur rathi]

Hi Jacquie,

Could you or anybody please tell me is there any diffrence between information hiding and encapsulation?

I think both are same.

Thanks.

[Paul Sturrock]

The two are (kind of) synonymous. Though of course an Object can contain methods as well as data, so "information hiding" is a poor choice of terminology to use. Where did you come across it?

[Ilja Preuss]

Information hiding is one way we implement encapsulation.

[Paul Sturrock]

Fair enough. Not a term I'd heard before - but I did come across this after a quick google.

[Jacquie Barker]

I use the term "information hiding" in an OOP context to refer to the fact that many details of a class are "hidden", namely:

- private attributes
- private methods
- and, even for public methods, the implement of HOW the method works is, in a sense, private

Think of the term "information hiding" as meaning "hiding details about the inner workings of a class (of objects)".

I use the term "encapsulation" in an OOP context to refer to the fact that everything an object needs in order to fulfill its mission in an application is, in theory, encapsulated within the object, as either a piece of data (attribute), reference to another object that it can turn to for collaborative help (attribute), or as a method. However, we also know that by linking together objects at run time, we can empower them to do much more than any one object can do on its own, just like the employees in a corporation, or the cells in your body, or ants in an anthill, can accomplish more collectively than on their own.

I hope this helps!

Jacquie

[Ilja Preuss]

Originally posted by Paul Sturrock:
Fair enough. Not a term I'd heard before - but I did come across this after a quick google.

Seems like there actually is no generally agreed upon definition of both terms... :roll:

[Jacquie Barker]

Originally posted by Ilja Preuss:


Seems like there actually is no generally agreed upon definition of both terms... :roll:

As is true of so much terminology!!!

Yet another way that I've talked about encapsulation is as a benefit of information hiding: namely, if we change a private detail -- data structure or internal workings of a method -- of a class, then the changes are "encapsulated"/bounded/contained within the class itself -- i.e., there are no "ripple effects" on the application as a whole.

Looking up encapsulation on
dictionary.com, I found:

1. The condition of being enclosed (as in a capsule);

2. The ability to provide users with a well-defined interface
to a set of functions in a way which hides their internal
workings. In object-oriented programming, the technique of
keeping together data structures and the methods (procedures)
which act on them.

Best,

J.
[ July 15, 2005: Message edited by: Jacquie Barker ]