[Modeling-users] New feature: PyModel

[Sebastien B. <sbi...@us...>]

        Hi all,

  I'm glad to announce that the cvs brch used to develop the PyModel
  (model expressed in plain python, rather than in an explicit xml file)
  is now explicitly closed; it has been integrated to the main trunk
  yesterday. It will included in the next release.

  PyModels are an *alternative* for xml models; both directly map to
  Modeling.Model instances when loaded at runtime. Both formats are and
  will be supported in the future.

  Many thanks to Mario who kept hassling me about a nicer and handier
  model representation than xml ;) and to all those who discussed the
  new feature.

Since it will probably take some time before the documentation initiated
by Mario is finalized,  here is a overview of what has been done, and
what still needs to be done.

- The three scripts mdl_generate_python_code.py,
  mdl_generate_DB_schema.py and mdl_validate_model.py have been adapted
  to take either an xmlmodel or a pymodel as their argument.

- Examples PyModels are integrated into testPackages, see
  Modeling/tests/testPackages/AuthorBooks/pymodel_AuthorBooks.py and
  Modeling/tests/testPackages/StoreEmployees/pymodel_StoreEmployees.py

- Reminder: you can find more informations by referring to the thread
  where we discussed the PyModels:
https://sourceforge.net/mailarchive/forum.php?thread_id=3D1702463&forum_id=
=3D10674
https://sourceforge.net/mailarchive/forum.php?thread_id=3D1703927&forum_id=
=3D10674
https://sourceforge.net/mailarchive/forum.php?thread_id=3D1755270&forum_id=
=3D10674

- There is no script converting xml models to pymodels yet. Hence, the
  ZModeler still only dumps xml models. This will be integrated in the
  next release, probably mdl_convert_model.py

Backward incompatibility: none intended, and none observed for the time
  being. Existing projects will continue to work as expected.

Loading a model
---------------
  If you try the cvs version, you'll probably notice that method
  ModelSet.loadModel() (used in generated __init__.py, probably in your
  package as well) has been deprecated. It has been moved to module
  Model.loadModel().  The new scheme for loading a model (supporting
  PyModels as well as xml models), as included in __init__.py for
  generated packages, is shorter than the previous one:

------------------------------------------------------------------------
# Load the model
MODEL_NAME=3D'your_model_name'
from Modeling import ModelSet, Model
if ModelSet.defaultModelSet().modelNamed(MODEL_NAME) is None:
  import os
  mydir =3D os.path.abspath(os.path.dirname(__file__))
  model=3DModel.searchModel(MODEL_NAME, mydir, verbose=3D0)
  if not model:
    import warnings
    warnings.warn("Couldn't load model %s'%MODEL_NAME)
  else:
    ModelSet.defaultModelSet().addModel(model)
------------------------------------------------------------------------

  (see docstring for Model.searchModel() for details)

Known bugs:
-----------

  Only one for the moment being: if you need to load more than one
  PyModel at runtime, you'll probably encounter strange behaviour; this
  is due to defaults leaking from one model to the other one. A quick
  fix is to add: 'import PyModel; reload(PyModel)' before loading the
  pymodel.


  It'd be great if some of you could spend some time to test it and
  report. For those who do not want to use pserver-based cvs (which too
  often ends up with EOF received from sf), a cvs snapshot can be
  downloaded at:
http://modeling.sourceforge.net/download/ModelingCore-0.9-pre-9.PyModel.tar=
.gz

  And feel free to ask for more informations!

        Regards,

-- S=E9bastien.