Editing Computer program (section)

===Program modules===
[[Modular programming]] is a technique to refine ''imperative language'' programs. Refined programs may reduce the software size, separate responsibilities, and thereby mitigate [[software aging]]. A ''program module'' is a sequence of statements that are bounded within a [[Block (programming)|block]] and together identified by a name.<ref name="se-ch8-216">{{cite book
  | last = Schach
  | first = Stephen R.
  | title = Software Engineering
  | publisher = Aksen Associates Incorporated Publishers
  | year = 1990
  | page = 216
  | isbn = 0-256-08515-3
}}</ref> Modules have a ''function'', ''context'', and ''logic'':<ref name="se-ch8-219">{{cite book
  | last = Schach
  | first = Stephen R.
  | title = Software Engineering
  | publisher = Aksen Associates Incorporated Publishers
  | year = 1990
  | page = 219
  | isbn = 0-256-08515-3
}}</ref>

* The ''function'' of a module is what it does.
* The ''context'' of a module are the elements being performed upon.
* The ''logic'' of a module is how it performs the function.

The module's name should be derived first by its ''function'', then by its ''context''. Its ''logic'' should not be part of the name.<ref name="se-ch8-219"/> For example, <code>function compute_square_root( x )</code> or <code>function compute_square_root_integer( i : integer )</code> are appropriate module names. However, <code>function compute_square_root_by_division( x )</code> is not.

The degree of interaction ''within'' a module is its level of [[Cohesion (computer science)|cohesion]].<ref name="se-ch8-219"/> ''Cohesion'' is a judgment of the relationship between a module's name and its ''function''. The degree of interaction ''between'' modules is the level of [[Coupling (computer science)|coupling]].<ref name="se-ch8-226">{{cite book
  | last = Schach
  | first = Stephen R.
  | title = Software Engineering
  | publisher = Aksen Associates Incorporated Publishers
  | year = 1990
  | page = 226
  | isbn = 0-256-08515-3
}}</ref> ''Coupling'' is a judgement of the relationship between a module's ''context'' and the elements being performed upon.