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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158B.4.PreconditionFunctions B.4.3ConditionalExceptions Thefollowingpreconditionstestwhethertheoperationiscapableofraising certainexceptionsinadditiontoitsst<strong>and</strong>ardset. rangeerror(source,result):Thispreconditionappearsonlywith orfor...inspectstatementwhosebodyincludesthecurrentoperation.<br />
uncopyable(oper<strong>and</strong>):Atypeispotentiallyuncopyableifitisan duplicatekey(table):Ifthetablehaskeys,thenaDuplicateKey inputportorcallmessagetype(whichareactuallyuncopyable),a exceptionispossible. conversionofeveryvalueinthedomainofsource,thenaRangeError<br />
theconvertoperation.Ifthedomainofresultdoesnotincludethe<br />
B.5PostconditionFunctions ablecomponenttypes,oratabletypewithapotentiallyuncopyable elementtype.Ifoper<strong>and</strong>isofapotentiallyuncopyabletype,thenthe polymorphtype,arecordorvarianttypewithpotentiallyuncopy-<br />
completionofanoperation.Eachfunctioncancauseattributestobeadded <strong>and</strong>/ordropped. Thefollowingfunctionsdeterminehowthetypestatechangesonnormal Uncopyableexceptionispossible.<br />
makeinit(oper<strong>and</strong>):Addtheattributeinit(oper<strong>and</strong>). makeuninit(oper<strong>and</strong>):Dropallattributesinvolvingoper<strong>and</strong>orits makefull(oper<strong>and</strong>):Addtheattributeinit(oper<strong>and</strong>).Inaddition, movets(source,destination):Foreachattributeinvolvingsourceora ifoper<strong>and</strong>isarecordorcallmessage,makeallitscomponentsrecursivelyfull.<br />
subcomponents. allotherattributesinvolvingdestinationvariableorasubcomponent. subcomponent. source,<strong>and</strong>addthesubstitutedattributeifnotalreadypresent.Drop subcomponent:(1)droptheattribute,(2)substitutedestinationfor Dropallconstraintattributesofvariablesofwhichdestinationisa
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