Coupling

Introduction

Coupling(English:Coupling,dependency,orCouplingforceorCoupling)isasoftwaremetric,whichreferstothedegreeofdependenceoninformationorparametersbetweenmodulesandmodulesinaprogram.

Cohesionisaconceptoppositetocoupling.Generallyspeaking,lowcouplingmeanshighcohesion,andviceversa.CouplingandcohesionarebothproposedbyLarryConstantinewhoproposedtheconceptofstructureddesign.Lowcouplingisacharacteristicofwell-structuredprograms,andthereadabilityandmaintainabilityoflow-couplingprogramswillbebetter.

Classificationofcoupling

Couplingcanbelowcoupling(orloosecoupling)orhighcoupling(ortightcoupling).Herearesomecategoriesofcoupling,arrangedinorderfromhightolow:

• Contentcoupling(contentcoupling,thehighestdegreeofcoupling)

• Itisalsocalledpathologicalcouplingwhenamoduledirectlyusestheinternaldataofanothermodule,ortransfersitintoanothermodulethroughanabnormalentry.

• Sharedcoupling/commoncoupling

• Alsoknownasglobalcoupling.Thecouplingbetweenthemodulesinteractingwiththecommondataenvironment.Thecomplexprogramofpubliccouplingincreaseswiththeincreaseofthenumberofcouplingmodules.

• Externalcoupling

• Itoccurswhentwomodulesshareanadditionaldataformat,communicationprotocolorThedeviceinterfaceisbasicallyrelatedtothecommunicationbetweenthemoduleandexternaltoolsandequipment.

• Controlcoupling

• Whenamodulecallsanothermodule,itpassescontrolvariables(suchasSwitch,flag,etc.),themodulatedmoduleselectivelyexecutesafunctionintheblockthroughthevalueofthecontrolvariable;

• featurecoupling/stampcoupling

• p>

• Alsoknownasdatastructurecoupling,itmeansthatseveralmodulesshareacomplexdatastructure,suchasarraynames,recordnames,andfilenamesinhigh-levellanguages.Thesenamesaretags.Infact,whatispassedistheaddressofthisdatastructure;

• Datacoupling/datacoupling

• referstothemoduleSharingdatabypassinginvalues,eachdataisthemostbasicdata,andonlysharingthesedata(forexample,passinganintegertothefunctionthatcalculatesthesquareroot).

• Messagecoupling(messagecouplingisthecouplingwiththelowestdegreeofcouplingbesidesnocoupling)

• YoucanusethefollowingTherearetwowaystoachievethis:decentralizationofstate(forexample,inobjects),andcommunicationbetweencomponentsusingincomingvalues​​ormessagepassing(computerscience).

• Nocoupling:Themoduledoesnotexchangeinformationwithothermodulesatall.

Object-orientedprogramming

• Subclasscoupling

• Describetherelationshipbetweenthechildclassandtheparentclass.Thechildclassislinkedtotheparentclass,buttheparentclassisnotlinkedtothechildclass.

• temporalcoupling

• Thetwoactionsarepackagedinonemoduleonlybecausetheyhappenatthesametime.

Laterresearchhasproposedmanydifferentlevelsofcoupling,andusedtoevaluatetheimplementationdegreeofvariousmodularlawsinpractice.

Disadvantages

Thetightlycoupledsystemhasthefollowingdisadvantagesinthedevelopmentphase:

1. Modificationsofonemodulewillproducerippleeffects,othersThemodulealsoneedstobemodifiedaccordingly.

2. Becauseofthedependenciesbetweenmodules,thecombinationofmoduleswillrequiremoreeffortandtime.

3. Sinceamodulehasmanydependentmodules,thereusabilityofthemoduleislow.

Improvementmethod

Functionaldesignisamethodthatcanreducecoupling.ThismethodtriestolimittheresponsibilityofeachmodulefromafunctionalperspectiveAffairs.BetweenthecategoriesAandB,ifanyofthefollowingsituationsexists,thecouplingbetweenthetwowillbeimprovedSex:

• AThereisanattributeofreferencecategoryB(TheformofthisattributeiscategoryB)

• ACalltheserviceprovidedbytheobjectB

• AThereisamethodthatreferstothecategoryB(thismethodwillreturnaphysicalpropertyofthecategoryB)

• AisasubcategoryofcategoryB.

Loosecouplingreferstotwomodulesrelatedtoeachother,theinterfaceofwhichisasimpleandstableinterface,anditsinterfacehasnothingtodowiththeinternalimplementationofanymodule(Referenceinformationhiding).

SystemslikeCORBAorComponentObjectModelallowanobjecttointeractwithanotherobjectwithoutknowinghowtheotherobjectisimplemented.Suchsystemsevenallowanobjecttointeractwithobjectswritteninotherlanguages.

Couplingandcohesion

Thetwotermscouplingandcohesionoftenappeartogethertoindicatethecharacteristicsthatanidealmoduleneeds,thatis,lowcouplingandHighcohesion.Couplingfocusesonthedependencebetweendifferentmodules,whilecohesionfocusesontherelationshipbetweendifferentfunctionsinamodule.Lowcohesionmeansthatthereisnorelationshipbetweenthefunctionsinamodule,andproblemsoftenoccurwhenthemoduleisexpanded.

Relateditems

• Dependencyhell

• Outgoingcoupling

• Cohesion(ComputerScience)

• ListofObject-OrientedProgrammingTerms

• make

• Staticprogramanalysis

• Inversionofcontrol

• Looselycoupled