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Class MosKey

Class MosKey provides part of the Muq support for the Muq Object System model of object-oriented computation. It is an internal support class normally only directly visible to -- or of interest to -- programmers venturing deep into the internals of Muq compilers and runtimes.

The MOS model requires that

Muq meets these requirements by implementing MOS generic functions as normal compiledFunction instances which happen to have (among other things) a special bit set identifying them as a MOS compiledFunction, and to have in their first constant slot a pointer to a MosKey instance, which then contains the time-varying information such as the currently-defined set of methods for the generic function.

A MosKey instance is itself neither a function nor a compiledFunction: It is merely a passive datastructure containing information about the generic function encoded for quick access during method invocation ("message-sending").

Class MosKey adds the following properties to those of Class Plain:

( Buggo, should merge type and layout, I think: )
$S.abstract              Normally NIL; non-NIL to forbid creation of instances.
$S.type                  'vector 'list or nil
$S.layout                Ram layout: :structure :vector :built-in :fixnum ...
$S.compiler              Parallel to function$s.compiler
$S.documentation         Value supplied to ]defclass :documentation option.
$S.source                Parallel to function$s.source
$S.fileName             Parallel to function$s.fileName
$S.fnLine               Parallel to function$s.fnLine
$S.assertion             Type verification compiledFunction.
$S.predicate             Type check compiled-funciton.
$S.printFunction        Print function.
$S.createdAnInstance   NIL unless an instances has been created.
$S.mosClass             Backpointer to MOS class we implement.
$S.newerKey             NIL, else pointer to key superceding us.
$S.concName             Prefix for accessor functions.
$S.constructor           Constructor compiledFunction.
$S.copier                Copier compiledFunction.
$S.named                 t or nil
$S.initialOffset        whole number
$S.export                NIL unless defstruct included :export t option.
$S.fertile               NIL unless subclassing by other users is ok.
$S.unsharedSlots        # of unshared slots (those stored in key).
$S.sharedSlots          # of shared slots (those stored in instances).
$S.mosParents           # of direct superclasses.
$S.mosAncestors         # of direct and indirect superclasses.
$S.initargs              # of initarg -> slotname map pairs.
$S.objectMmethods        # of methods keying on obj of our class in 1st arg.
$S.classMethods         # of methods keying on our class in 1st arg.
$S.metaclass             Currently always standardClass.

Note: For convenience, the $S properties are also available in the public (default) propdir.

MosKey instances also contain internal arrays with the above dimensions, in particular, the class precedence list: See section getMosKeyInitarg. See section getMosKeyInitarg. See section getMosKeyParent. See section setMosKeyParent. See section getMosKeyAncestor. See section setMosKeyAncestor. See section getMosKeySlotProperty. See section setMosKeySlotProperty.

See section makeMosKey.

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