Have you wished for a completely Dummy object, one that you can do whatever you want to it? One you can return and all expressions will work?
No???
Hmm.. ok. But here it is anyway.
Python, 36 lines
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Copy to clipboard1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 | class Dummy(object):
def __getattr__(self, attr):
try:
return super(self.__class__, self).__getattr__(attr)
except AttributeError:
if attr in ('__base__', '__bases__', '__basicsize__', '__cmp__',
'__dictoffset__', '__flags__', '__itemsize__',
'__members__', '__methods__', '__mro__', '__name__',
'__subclasses__', '__weakrefoffset__',
'_getAttributeNames', 'mro'):
raise
else:
return self
def next(self):
raise StopIteration
def __repr__(self):
return 'Dummy()'
def __init__(self, *args, **kwargs):
pass
def __len__(self):
return 0
def __eq__(self, other):
return self is other
def __hash__(self):
return hash(None)
def __call__(self, *args, **kwargs):
return self
__sub__ = __div__ = __mul__ = __floordiv__ = __mod__ = __and__ = __or__ = \
__xor__ = __rsub__ = __rdiv__ = __rmul__ = __rfloordiv__ = __rmod__ = \
__rand__ = __rxor__ = __ror__ = __radd__ = __pow__ = __rpow__ = \
__rshift__ = __lshift__ = __rrshift__ = __rlshift__ = __truediv__ = \
__rtruediv__ = __add__ = __getitem__ = __neg__ = __pos__ = __abs__ = \
__invert__ = __setattr__ = __delattr__ = __delitem__ = __setitem__ = \
__iter__ = __call__
Dummy = Dummy()
|
You can now use Dummy anytime any object is required.
>>> a = Dummy() ; d = Dummy() ; j = Dummy(3)
>>> j **= (d + 3) * (a / j)
>>> print j is j('parameters', any='parameters').attribute.access.is_.allowed['and item']()()
True
>>> print (d < j, d > j, d == j)
(False, False, True)
>>> print sorted([Dummy(n + d) for n in xrange(3)]), sorted(a)
[Dummy(), Dummy(), Dummy()] []
>>> print '%d == %d == 0' % (len(a), len(list(a)))
0 == 0 == 0
see : Null in recipe 68205
Thanks for pointing me this recipe, Louis.
But since I use a different approach, testing for special attributes and overriding all main functions of objects. Null works only for attributes and calls, and raises errors for a lot of uses.
I guess that's why I named it Dummy, it can act as a list, or as a dict, or as anything else.