Editing Abstraction (computer science) (section)

==Abstraction features==

===Programming languages===
{{Further|Programming language}}

Different programming languages provide different types of abstraction, depending on the intended applications for the language. For example:

* In [[object-oriented programming]] languages such as [[C++]], [[Object Pascal]], or [[Java (programming language)|Java]], the concept of ''abstraction'' has become a declarative statement – using the [[Syntax (programming languages)|syntax]] <code>''function''(''parameters'') = 0;</code> (in [[C++]]) or the [[reserved word]]s (keywords) ''<code>abstract</code>''<ref name="Oracle Java abstract">{{cite web |url=http://docs.oracle.com/javase/tutorial/java/IandI/abstract.html |title=Abstract Methods and Classes|website=The Java Tutorials |publisher=Oracle |access-date=4 September 2014}}</ref> and ''<code>interface</code>''<ref name="Oracle Java interface">{{cite web |url=http://docs.oracle.com/javase/tutorial/java/IandI/interfaceAsType.html |title=Using an Interface as a Type|website=The Java Tutorials |publisher=Oracle |access-date=4 September 2014}}</ref> (in [[Java (programming language)|Java]]). After such a declaration, it is the responsibility of the programmer to implement a [[Class (computer science)|class]] to instantiate the [[Object (computer science)|object]] of the declaration.
* [[Functional programming]] languages commonly exhibit abstractions related to functions, such as [[lambda abstraction]]s (making a term into a function of some variable) and [[higher-order function]]s (parameters are functions).<ref>{{FOLDOC|Abstraction}}</ref><!-- This has to be merged in the following sections. -->
* Modern members of the [[List of Lisp-family programming languages|Lisp programming language family]] such as [[Clojure]], [[Scheme (programming language)|Scheme]] and [[Common Lisp]] support [[Macro (computer science)#Syntactic macros|macro systems]] to allow syntactic abstraction. Other programming languages such as [[Scala (programming language)|Scala]] also have macros, or very similar [[metaprogramming]] features (for example, [[Haskell]] has [[Template Haskell]], [[OCaml]] has [[MetaOCaml]]). These can allow programs to omit [[boilerplate code]], abstract away tedious function call sequences, implement new [[control flow]] structures, and implement [[domain-specific language]]s (DSLs), which allow domain-specific concepts to be expressed in concise and elegant ways. All of these, when used correctly, improve both the programmer's efficiency and the clarity of [[source code]] by making the intended purpose more explicit. A consequence of syntactic abstraction is also that any Lisp dialect, and almost any programming language, can in principle, be implemented in any modern Lisp with significantly reduced (but still non-trivial in most cases) effort when compared to "more traditional" programming languages such as [[Python (programming language)|Python]], [[C (programming language)|C]] or [[Java (programming language)|Java]].

===Specification methods===
{{Further|Formal specification}}

Analysts have developed various methods to formally specify software systems. Some known methods include:

* Abstract-model based method (VDM, Z);
* Algebraic techniques (Larch, CLEAR, OBJ, ACT ONE, CASL);
* Process-based techniques (LOTOS, SDL, Estelle);
* Trace-based techniques (SPECIAL, TAM);
* Knowledge-based techniques (Refine, Gist).

===Specification languages===
{{Further|Specification language}}

Specification languages generally rely on abstractions of one kind or another, since specifications are typically defined earlier in a project, (and at a more abstract level) than an eventual implementation. The [[Unified Modeling Language]] (UML) specification language, for example, allows the definition of ''abstract'' classes, which in a waterfall project, remain abstract during the architecture and specification phase of the project.