[Python-checkins] python/nondist/sandbox/datetime picklesize.py,NONE,1.1

2002年12月03日 09:50:12 -0800

Update of /cvsroot/python/python/nondist/sandbox/datetime
In directory sc8-pr-cvs1:/tmp/cvs-serv26946
Added Files:
	picklesize.py 
Log Message:
New program just to display pickle sizes. This makes clear that the
copy_reg based C implementation is much more space-efficient in the
end than the __getstate__/__setstate__ based Python implementation,
but that 4-byte date objects still suffer > 10 bytes of overhead each
no matter how many of them you pickle in one gulp.
It also makes clear a bug in timedelta: str() doesn't work the same
across the implementations.
--- NEW FILE: picklesize.py ---
import datetime, _datetime
if 1:
 import cPickle as pickle
else:
 import pickle
cases = (datetime, "Python"), (_datetime, "C")
def pickleit(thing):
 s = pickle.dumps(thing, 1)
 return len(s)
typenames = "date", "datetime", "timedelta"
for typename in typenames:
 for mod, way in cases:
 obj = getattr(mod, typename)(2000, 12, 13)
 print "pickling", obj, "via", way, "-- pickle length", pickleit(obj)
for typename in typenames:
 for i in range(1, 11):
 for mod, way in cases:
 ctor = getattr(mod, typename)
 objs = [ctor(j+1, 3, 4) for j in range(i**2)]
 plen = pickleit(objs)
 print "list of %3d %ss via %6s -- %4d bytes, %5.2f bytes/obj" % (
 len(objs), typename, way, plen, float(plen)/len(objs))