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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Inspect-polymorph willincludefinit(name)g.Componentnamewillbediscardedbeforemovingthewrappedvalueintox.Theresultingtypestatewillbefinit(x),<br />
Thetypeswillmatch,buttheformaltypestateinthewrapperofy 11.<strong>Hermes</strong>Operations127 init(x.id),positive(x.id)g. compound{statement ::=inspectdeclaration<br />
morphisconstant. ceptthatinsteadofmovingthewrappedvalue,aconstantcopyismade. Theinspect-polymorphstatementbehaveslikeanunwrapstatementex-<br />
Thisallowsthevalueofapolymorphtobeexamined,evenifthepoly-<br />
endinspect begin [statement;]... frompolymorph{expressioninspect{typestate<br />
whichwouldbelegalevenifthepolymorphywereconstant: Hereisanalternativeversionoftheunwrapstatementshownabove,<br />
wouldnotbeaccessible,sincethetypestateinsidethestatementwouldbe thatcomponentwouldnotbediscardedintheconstantcopyx,butit inspectx:personfromyfinit(*),init(id),positive(id)g<br />
operation. simplyfinit(y)init(x),init(x.id),positive(x.id)g. Assumingthatthewrappedvaluehadaninitializedcomponentname, TheexceptionPolymorphMismatchisraisedexactlyasforanunwrap endinspect; begin .../*statementsreferringtox*/<br />
Type morphwrapper.Thisisaninitializedvalueoftypepredefined!typeofvalue. Thetypeofoperationevaluatestothetypeinformationstoredinthepoly-<br />
Thevalueincludesthetypename,thedenitionsmoduledeningthetype name,<strong>and</strong>alltheimporteddenitionsmodules. Theoper<strong>and</strong>mustbeaninitializedpolymorph. secondary::=typeofsecondary Typestate secondary::=typestateofsecondary
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