E&S CVS Commit: pylib - Added new "Basic" structural model, designed to be structure-agnostic and

[pje at eby-sarna.com]

Module Name:	pylib
Committed By:	pje
Date:		Mon Jul 30 21:18:34 UTC 2001

Added Files:
	pylib/TW/StructuralModel: Basic.py

Log Message:
Added new "Basic" structural model, designed to be structure-agnostic and
capable of being used with weak references, acquisition, persistence, or
other methods of dodging circular references.  Services and Features in the
Basic model automatically copy themselves on first use so that each
container gets a fresh instance.  This allows features to directly contain
or manage their data, rather than having to delegate back to a higher
level.  (Which is much more convenient for simple storage models like a
purely-in-memory application or a ZODB-based app.)

Also added a simple implementation of the Basic model, "AcquisitionModel",
which uses Acquisition to link Features and Elements back to their Elements
and Services, respectively.  It does not break circular links on its own,
but must be used with a garbage-collecting VM (e.g. Jython or Python 2.1)
or with ZODB, in order to avoid memory leaks.


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cvs rdiff -r0 -r1.1 pylib/TW/StructuralModel/Basic.py

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