adding nefertari.engine

nefertari/engine/__init__.py

@@ -0,0 +1,49 @@
+"""
+Extend global scope with an engine-specific variables/objects.
+
+Usage
+-----
+
+  0. Provide 'nefertari.engine' setting in your .ini
+  1. Include 'nefertari.engine' in your app's root 'includeme' as soon after
+    `Configurator` setup as possible and BEFORE importing anything from
+    nefertari.engine
+  <- At this point you may import from nefertari.engine ->
+  2. Include your models
+  3. Perform database schema, engine, etc setup. Or use
+    `nefertari.engine.setup_database`.
+
+Notes
+-----
+
+Db setup should be performed after loading models, as some engines require
+models schema to be defined before creating the database. If your database
+does not have above requirement, it's up to you to decide when to setup
+db.
+
+The specified engine module is also `config.include`d here thus running
+engine's `icludeme` function and allowing setting up required state,
+performing some actions, etc.
+
+Specified engine may be either module or package.
+In case you build a custom engine, variables you expect to use from it,
+should be importable from package itself.
+E.g. ``from your.package import BaseDocument``
+
+nefertari relies on 'nefertari.engine' being included when configuring the app.
+"""
+
+from zope.dottedname.resolve import resolve
+
+
+def includeme(config):
+    def _valid_global(g):
+        ignored = ('log', 'includeme')
+        return (not g.startswith('__') and g not in ignored)
+
+    engine_path = config.registry.settings['nefertari.engine']
+    config.include(engine_path)
+    engine_module = resolve(engine_path)
+    engine_globals = {k: v for k, v in engine_module.__dict__.iteritems()
+                      if _valid_global(k)}
+    globals().update(engine_globals)