SPREE-OBJSTORE(2) SPREE-OBJSTORE(2)
NAME
Objstore - support for object archiving in Spree engines.
SYNOPSIS
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;
DESCRIPTION
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 vari-
able 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(o, name), or nil if there was none such.
The names for an object are stored in the attribute ``ยง'',
which is cleared when unarchive is called.
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