Nov 10, 2003
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- Introduction to data abstraction and OOP

- Data abstraction typically involves
	- encapsulation
		(put everything in one place)
	- information-hiding
		(don't expose details needlessly)
	=> often clubbed together 
		   as "abstract data types"

- OOP typically adds to this mix
	- inheritance
	- dynamic method binding

- Data abstraction: available in
	- Ada, Modula, C++, Java, EUCLID

- Example ADT: Stack
	- defined by interface

- Example Stack operations
	- push
	- pop
	- top
	- isempty

- Can define Stack by some "Axioms"
	- pop(push(stack,element)) = stack
	- top(push(stack,element)) = element
	- isempty(create) = true
	- ...

- Examples of ADT implementations
	- Ada
	- C++
	- Java

- Ada
	- called "packages"
		- specification
		- implementation
	- but packages can be anything thrown together
	- private, public, and limited private members
	- no constructors or destructors 

- C++
	- called "structs" or "classes"
		- difference lies in default access patterns
	- public, private, protected
	- both stack and heap allocation possible
	- constructors and destructors can both be defined

- Java
	- called "classes"
	- ditto
	- only constructor provided, no destructors (why?)

- can also have "templates"
	- parameterized ADTs