Caching a list of data using pickle

picklecache.py

'''
Example for caching a list of data using pickle.
'''
import cPickle as pickle

_CachePath = '/tmp/cache.pkl'

def expensiveToComputeData():
	# These would be date retrieved from an external file involving lots fo
	# computations, validation and so on. This particular example data are
	# obviously easy to "compute".
	return [
		[123, 'hugo', '1965-03-27'],
		[234, 'resi', '1983-09-02'],
		[987, 'sepp', '2004-02-28'],
	]

def writeCachedData():
	with open(_CachePath, 'wb') as cacheFile:
		pickler = pickle.Pickler(cacheFile, pickle.HIGHEST_PROTOCOL)
		for row in expensiveToComputeData():
			pickler.dump(row)
		pickler.dump(None)

def cachedData():
	with open(_CachePath, 'rb') as cacheFile:
		unpickler = pickle.Unpickler(cacheFile)
		row = unpickler.load()
		while row is not None:
			yield row
			row = unpickler.load()

if __name__ == '__main__':
	writeCachedData()
	for row in cachedData():
		print row