Files
example-code-2e/appendix-A/schedule2.py
2020-01-22 22:52:23 -03:00

133 lines
3.3 KiB
Python

"""
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)
>>> event = DbRecord.fetch('event.33950')
>>> event
<Event 'There *Will* Be Bugs'>
>>> event.venue
<DbRecord serial='venue.1449'>
>>> event.venue.name
'Portland 251'
>>> for spkr in event.speakers:
... 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
import osconfeed
DB_NAME = 'data/schedule2_db'
CONFERENCE = 'conference.115'
class Record:
def __init__(self, **kwargs):
self.__dict__.update(kwargs)
def __eq__(self, other):
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."""
class DbRecord(Record):
__db = None
@staticmethod
def set_db(db):
DbRecord.__db = db
@staticmethod
def get_db():
return DbRecord.__db
@classmethod
def fetch(cls, ident):
db = cls.get_db()
try:
return db[ident]
except TypeError:
if db is None:
msg = "database not set; call '{}.set_db(my_db)'"
raise MissingDatabaseError(msg.format(cls.__name__))
else:
raise
def __repr__(self):
if hasattr(self, 'serial'):
cls_name = self.__class__.__name__
return '<{} serial={!r}>'.format(cls_name, self.serial)
else:
return super().__repr__()
# END SCHEDULE2_DBRECORD
# BEGIN SCHEDULE2_EVENT
class Event(DbRecord):
@property
def venue(self):
key = 'venue.{}'.format(self.venue_serial)
return self.__class__.fetch(key)
@property
def speakers(self):
if not hasattr(self, '_speaker_objs'):
spkr_serials = self.__dict__['speakers']
fetch = self.__class__.fetch
self._speaker_objs = [fetch('speaker.{}'.format(key))
for key in spkr_serials]
return self._speaker_objs
def __repr__(self):
if hasattr(self, 'name'):
cls_name = self.__class__.__name__
return '<{} {!r}>'.format(cls_name, self.name)
else:
return super().__repr__()
# 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]
cls_name = record_type.capitalize()
cls = globals().get(cls_name, DbRecord)
if inspect.isclass(cls) and issubclass(cls, DbRecord):
factory = cls
else:
factory = DbRecord
for record in rec_list:
key = '{}.{}'.format(record_type, record['serial'])
record['serial'] = key
db[key] = factory(**record)
# END SCHEDULE2_LOAD