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Objstore - support for object archiving in Spree engines.


include "spree.m";
include "spree/objstore.m";
Object: import Spree;
objstore := load Objstore Objstore->PATH;

init:       fn(m: Spree, c: ref Clique);
setname:    fn(o: ref Object, name: string);
unarchive:  fn();
get:        fn(name: string): ref Object;


The spree(2) module provides an Archives module to allow storage of an engine's object hierarchy to a persistent medium. This does not store the state internal to an engine that is not reflected in the object hierarchy, e.g. global variables. In particular, if an engine holds a variable referring to an object, it is not able to reset that variable correctly when the archive is later restored. The Objstore module provides some support for the naming of objects before archival, and for their retrieval by name, in order to enable this.

Init must be called first with the spree module, m, and the current clique, c. When a module is archiving itself, it should name each object that it wishes to retrieve, using setname. It is permissible for a single object to be given multiple names: the object will later be retrievable under any of its given names.

When restoring from an archive, a module should call unarchive, which scans through the object hierarchy looking for named objects and storing their names. After this, get(name) will return the object, o, that was named name by a previous setname(oname), or nil if there was none such.

The names for an object are stored in the attribute ``§'', which is cleared when unarchive is called.

SPREE-OBJSTORE(2 ) Rev:  Thu Feb 15 14:43:26 GMT 2007