On Oct 24, 5:19 pm, [EMAIL PROTECTED] wrote:
> Tim Golden napisa (a):
>
> > It's only a moment before the metaclass and
> > the Twisted solution come along. :)
>
> I couldn't resist. It's not as elegant as I hoped, but hey, at least
> it memoizes the intermediate classes :-)
>
> class fact_0(object):
> value = 1
>
> class fact_meta(object):
> def __new__(cls, name, bases, attrs):
> n = attrs['n']
> class_name = 'fact_%i' % n
> try:
> return globals()[class_name]
> except KeyError:
> new_class = type(class_name, bases, {})
> new_class.value = n * fact(n - 1).value
> new_class.__str__ = lambda self: str(self.value)
> globals()[class_name] = new_class
> return new_class
>
> class fact(object):
> def __new__(self, n_):
> class spanish_inquisition(object):
> __metaclass__ = fact_meta
> n = n_
> return spanish_inquisition()
>
> print fact(5)
> print fact(3)
> print fact(1)
Dare I add fact(0)?
120
6
1
<__main__.fact_0 object at 0x011729F0>
Hmm..not sure what that means, but I bet I can't calculate
combinations.
What about fact(-1)?
120
6
1
<__main__.fact_0 object at 0x011729F0>
Traceback (most recent call last):
File "C:/Program Files/PyGTK/Python/user/yet_another_factorial.py",
line 31, in <module>
print fact(-1)
File "C:/Program Files/PyGTK/Python/user/yet_another_factorial.py",
line 21, in __new__
class spanish_inquisition(object):
File "C:/Program Files/PyGTK/Python/user/yet_another_factorial.py",
line 13, in __new__
new_class.value = n * fact(n - 1).value
File "C:/Program Files/PyGTK/Python/user/yet_another_factorial.py",
line 21, in __new__
class spanish_inquisition(object):
File "C:/Program Files/PyGTK/Python/user/yet_another_factorial.py",
line 13, in __new__
new_class.value = n * fact(n - 1).value
File "C:/Program Files/PyGTK/Python/user/yet_another_factorial.py",
line 21, in __new__
class spanish_inquisition(object):
File "C:/Program Files/PyGTK/Python/user/yet_another_factorial.py",
line 13, in __new__
new_class.value = n * fact(n - 1).value
File "C:/Program Files/PyGTK/Python/user/yet_another_factorial.py",
line 21, in __new__
class spanish_inquisition(object):
File "C:/Program Files/PyGTK/Python/user/yet_another_factorial.py",
line 13, in __new__
new_class.value = n * fact(n - 1).value
File "C:/Program Files/PyGTK/Python/user/yet_another_factorial.py",
line 21, in __new__
class spanish_inquisition(object):
File "C:/Program Files/PyGTK/Python/user/yet_another_factorial.py",
line 13, in __new__
new_class.value = n * fact(n - 1).value
File "C:/Program Files/PyGTK/Python/user/yet_another_factorial.py",
line 21, in __new__
class spanish_inquisition(object):
File "C:/Program Files/PyGTK/Python/user/yet_another_factorial.py",
line 13, i
Wow! An infinite loop in the Traceback. Not quite the exception
I was looking for.
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