updated from Atlas

19-dyn-attr-prop/oscon/schedule2.py

@@ -0,0 +1,132 @@
+"""
+schedule2.py: traversing OSCON schedule data
+
+    >>> import shelve
+    >>> db = shelve.open(DB_NAME)
+    >>> if CONFERENCE not in db: load_db(db)
+
+# BEGIN SCHEDULE2_DEMO
+
+    >>> DbRecord.set_db(db)  # <1>
+    >>> event = DbRecord.fetch('event.33950')  # <2>
+    >>> event  # <3>
+    <Event 'There *Will* Be Bugs'>
+    >>> event.venue  # <4>
+    <DbRecord serial='venue.1449'>
+    >>> event.venue.name  # <5>
+    'Portland 251'
+    >>> for spkr in event.speakers:  # <6>
+    ...     print('{0.serial}: {0.name}'.format(spkr))
+    ...
+    speaker.3471: Anna Martelli Ravenscroft
+    speaker.5199: Alex Martelli
+
+# END SCHEDULE2_DEMO
+
+    >>> db.close()
+
+"""
+
+# BEGIN SCHEDULE2_RECORD
+import warnings
+import inspect  # <1>
+
+import osconfeed
+
+DB_NAME = 'data/schedule2_db'  # <2>
+CONFERENCE = 'conference.115'
+
+
+class Record:
+    def __init__(self, **kwargs):
+        self.__dict__.update(kwargs)
+
+    def __eq__(self, other):  # <3>
+        if isinstance(other, Record):
+            return self.__dict__ == other.__dict__
+        else:
+            return NotImplemented
+# END SCHEDULE2_RECORD
+
+
+# BEGIN SCHEDULE2_DBRECORD
+class MissingDatabaseError(RuntimeError):
+    """Raised when a database is required but was not set."""  # <1>
+
+
+class DbRecord(Record):  # <2>
+
+    __db = None  # <3>
+
+    @staticmethod  # <4>
+    def set_db(db):
+        DbRecord.__db = db  # <5>
+
+    @staticmethod  # <6>
+    def get_db():
+        return DbRecord.__db
+
+    @classmethod  # <7>
+    def fetch(cls, ident):
+        db = cls.get_db()
+        try:
+            return db[ident]  # <8>
+        except TypeError:
+            if db is None:  # <9>
+                msg = "database not set; call '{}.set_db(my_db)'"
+                raise MissingDatabaseError(msg.format(cls.__name__))
+            else:  # <10>
+                raise
+
+    def __repr__(self):
+        if hasattr(self, 'serial'):  # <11>
+            cls_name = self.__class__.__name__
+            return '<{} serial={!r}>'.format(cls_name, self.serial)
+        else:
+            return super().__repr__()  # <12>
+# END SCHEDULE2_DBRECORD
+
+
+# BEGIN SCHEDULE2_EVENT
+class Event(DbRecord):  # <1>
+
+    @property
+    def venue(self):
+        key = 'venue.{}'.format(self.venue_serial)
+        return self.__class__.fetch(key)  # <2>
+
+    @property
+    def speakers(self):
+        if not hasattr(self, '_speaker_objs'):  # <3>
+            spkr_serials = self.__dict__['speakers']  # <4>
+            fetch = self.__class__.fetch  # <5>
+            self._speaker_objs = [fetch('speaker.{}'.format(key))
+                                  for key in spkr_serials]  # <6>
+        return self._speaker_objs  # <7>
+
+    def __repr__(self):
+        if hasattr(self, 'name'):  # <8>
+            cls_name = self.__class__.__name__
+            return '<{} {!r}>'.format(cls_name, self.name)
+        else:
+            return super().__repr__()  # <9>
+# END SCHEDULE2_EVENT
+
+
+# BEGIN SCHEDULE2_LOAD
+def load_db(db):
+    raw_data = osconfeed.load()
+    warnings.warn('loading ' + DB_NAME)
+    for collection, rec_list in raw_data['Schedule'].items():
+        record_type = collection[:-1]  # <1>
+        cls_name = record_type.capitalize()  # <2>
+        cls = globals().get(cls_name, DbRecord)  # <3>
+        if inspect.isclass(cls) and issubclass(cls, DbRecord):  # <4>
+            factory = cls  # <5>
+        else:
+            factory = DbRecord  # <6>
+        for record in rec_list:  # <7>
+            key = '{}.{}'.format(record_type, record['serial'])
+            record['serial'] = key
+            db[key] = factory(**record)  # <8>
+# END SCHEDULE2_LOAD