Editing Coupling (computer programming) (section)

=== Procedural programming ===
A module here refers to a subroutine of any kind, i.e. a set of one or more statements having a name and preferably its own set of variable names.

;{{anchor|Content coupling}}Content coupling (high): Content coupling is said to occur when one module uses the code of another module, for instance a branch. This violates [[information hiding]] – a basic software design concept.
;{{anchor|Common coupling}}Common coupling: Common coupling is said to occur when several modules have access to the same global data. But it can lead to uncontrolled error propagation and unforeseen side-effects when changes are made.
;{{anchor|External coupling}}External coupling: External coupling occurs when two modules share an externally imposed data format, communication protocol, or device interface. This is basically related to the communication to external tools and devices.
;{{anchor|Control coupling}}Control coupling: Control coupling is one module controlling the flow of another, by passing it information on what to do (e.g., passing a what-to-do flag).
;{{anchor|Stamp coupling|data-structured coupling}}Stamp coupling (data-structured coupling): Stamp coupling occurs when modules share a composite data structure and use only parts of it, possibly different parts (e.g., passing a whole record to a function that needs only one field of it).
:In this situation, a modification in a field that a module does not need may lead to changing the way the module reads the record. To illustrate the concept of stamp coupling, consider a scenario involving a <code>UserProfile</code> [[Software component|component]]. This component is designed to return the entire user profile information in response to [[HTTP|requests]], even when [[User agent|consumers]] only require a specific [[Attribute (computing)|attribute]]. This practice exemplifies stamp coupling, which can lead to significant [[Bandwidth (computing)|bandwidth]] issues, especially at scale. When any attribute within the <code>UserProfile</code> component changes, all consumers that interact with it may need to undergo [[Software testing|testing]], even if they do not utilize the modified attribute. <ref>{{Cite book |last=Richards |first=Mark |title=Fundamentals of Software Architecture: An Engineering Approach |publisher=O'Reilly Media |isbn=978-1492043454}}</ref>
;{{anchor|Data coupling}}Data coupling: Data coupling occurs when modules share data through, for example, parameters. Each datum is an elementary piece, and these are the only data shared (e.g., passing an integer to a function that computes a square root).