Hermes: A Tutorial and Reference Manual - Researcher - IBM
Hermes: A Tutorial and Reference Manual - Researcher - IBM
Hermes: A Tutorial and Reference Manual - Researcher - IBM
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12211.8.ProcessCreation<strong>and</strong>CommunicationOperations<br />
ingtheargumentsintothecallmessage,(3)sendingthecallmessageto theinputporttowhichtheoutputportisconnected,(4)waitingforthe nofunctioncallcanhaveanymodiableparameterexceptitsresult. arepartsofexpressions,<strong>and</strong>expressionsmaynotmodifytheiroper<strong>and</strong>s, procedurereturns4,youwillnotchangethevalueof3.)Sincefunctioncalls ables.Ifthesevariablesarepassedtomodiableparameters,themodica-<br />
tionsarelost.(Forexample,ifyoupass3toaninoutparameter,<strong>and</strong>the Thecallisexecutedby:(1)creatinganewcallmessagevalue;(2)mov-<br />
Itshouldbenotedthatexpressionsareevaluatedintotemporaryvari-<br />
callmessagetobereturned,(5)movingthecallmessagecomponentsback theneventuallythemessagewillbereceived. ismade,<strong>and</strong>thereceivingprocessrepeatedlyissuesreceivestatements, arereturnedinthesametypestatetheyweresent. ontheseoutputportsaremergedfairly.Thismeansthatifacallorsend intotheargumentvariables,(6)throwingawaythecallmessage. aportconnection,theDisconnectedexceptionisraised.Thearguments riedoutasinaregularcall,butadditionally,theexceptionisraisedinthe Ifthecallisreturnedwithanexception,thenalltheabovestepsarecar-<br />
Ifseveraloutputportsareconnectedtothesameinputport,thencalls<br />
caller.Thiscanonlyhappenifthereexistsadeclarationofthatexceptionin thecallmessagetypedenition.Thefullnamefortheexceptionincludesthe callmessagetype<strong>and</strong>theexceptionname|.. Iftheinputporthasbeenthrownaway,leavingtheoutputportwithout<br />
parametersareadded<strong>and</strong>dropped.Theseadds<strong>and</strong>dropsareappliedto betweentheentry<strong>and</strong>returntypestatesdeneswhichattributesofthe .Discardedisraisedinthecaller.Thecallmessageisreturned withtheparametersintheminimumtypestateasdenedinthecallmessage tatejustpriortothecall,fromtheentrytypestate,<strong>and</strong>fromthetypestate<br />
denedforthenormalorexceptionalreturnbeingmade.Thedierence Thetypestateafterexecutingacallstatementisderivedfromthetypes-<br />
Iftheprocessowningthecallmessagediscardsit,thentheexception<br />
theargumentsmatchingtheparameters. Forexample<br />
tionsampleinterface.Failure,thetypestatewillbefinit(p),init(a), constantparametersecond,itcannotretainitsattributeeven(b),which even(b),init(c)g.Sinceamatchestheconstantparameterfirst,it mayretainitsadditionalattributeeven(a).Sincebmatchesthenon-<br />
isdroppedpriortothecall.Onnormalreturnfromthecall,thetypestate willbefinit(p),init(a),even(a),init(b),init(d)g.Onexcep-<br />
typestatepriortothecallis:finit(p),init(a),even(a),init(b), callp(a,b,c,d);<br />
even(a),negative(a),init(b),init(c)g. Supposethetypeofpissampleoutport,denedabove.Supposethe
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