def getSize(obj):
"""Calculate the size as cheap as possible
"""
# Try the cheap variants first.
# Actually the checks ensure the code never fails but beeing sure
# is better.
try:
# check if to return zero (length is zero)
if len(obj) == 0:
return 0
except:
pass
try:
# check if ``IStreamableReference``
if IStreamableReference.isImplementedBy(obj):
size = obj.getSize()
if size is not None:
return size
except:
pass
try:
# string
if isinstance(obj, types.StringTypes):
return len(obj)
except:
pass
try:
# file like object
methods = dir(obj)
if "seek" in methods and "tell" in methods:
currentPos = obj.tell()
obj.seek(0, 2)
size = obj.tell()
obj.seek(currentPos)
return size
except:
pass
try:
# fallback: pickling the object
stream = StringIO()
p = Pickler(stream, 1)
p.dump(obj)
size = stream.tell()
except:
size = None
return size
