Data Abstraction & Function in CMSC 433 - Programming Language Technologies - Prof. Atif M, Study notes of Programming Languages

Download Data Abstraction & Function in CMSC 433 - Programming Language Technologies - Prof. Atif M and more Study notes Programming Languages in PDF only on Docsity! CMSC 433 – Programming Language Technologies and Paradigms Spring 2007 Abstraction Feb. 27, 2007 Data Abstraction • Data abstraction = objects + operations – List + { addFirst, addLast, removeFirst, ... } – Set + { add, contains, ...} • Categories of operations – Constructors (creators/producers) – Mutators/Modifiers – Observers Abstraction Function • Specification for data structure is abstract • Implementation of data structure is concrete • How do you know if implementation meets the spec? • Abstraction function : concrete abstract – Specifies how the representation of an abstract data type is interpreted as an abstract value. Example class IntSet { int[] elts; ... } – AF(s) = { s.elts[i] | 0 <= i <= elts.length } • You always need an abstraction function when you build a data abstraction – Often it’s implicit