suggestions, comments on an "is_subdict" test

Fri Apr 22 09:55:23 EDT 2011

Hi all,
I'd like to ask for comments or advice on a simple code for testing a
"subdict", i.e. check whether all items of a given dictionary are
present in a reference dictionary.
Sofar I have:
def is_subdict(test_dct, base_dct):
 """Test whether all the items of test_dct are present in base_dct."""
 unique_obj = object()
 for key, value in test_dct.items():
 if not base_dct.get(key, unique_obj) == value:
 return False
 return True
I'd like to ask for possibly more idiomatic solutions, or more obvious
ways to do this. Did I maybe missed some builtin possibility?
I am unsure whether the check against an unique object() or the
negated comparison are usual.?
(The builtin exceptions are ok, in case anything not dict-like is
passed. A cornercase like >>> is_subdict({}, 4)
>>> True
doesen't seem to be worth a special check just now.)
Thanks in advance for the suggestions,
 regards,
 vbr