I'm not 100% sure about this, but from what it seems like, the reason
method B worked, and not method a is because class foo(complex) is
subclassing a metaclass. So if you do this, you can't init a meta class
(try type(complex), it equals 'type' not 'complex'. type(complex())
yields 'complex'), so you use the new operator to generator a class on
the fly which is why it works in method B. I hope that's right.
-Brandon
> Spending the morning avoiding responsibilities, and seeing what it would
> take to color some complex numbers.
>
> class color_complex(complex):
> def __init__(self,*args,**kws):
> complex.__init__(*args)
> self.color=kws.get('color', 'BLUE')
>
>>>> a=color_complex(1,7)
>>>> print a
> (1+7j) #good so far
>>>> a=color_complex(1,7,color='BLUE')
> Traceback (most recent call last):
> File "<pyshell#37>", line 1, in -toplevel-
> a=color_complex(1,7,color='BLUE')
> TypeError: 'color' is an invalid keyword argument for this function
>
> No good... it seems that I am actually subclassing the built_in function
> 'complex' when I am hoping to have been subclassing the built_in numeric
> type - complex.
>
> but some googling sends me to lib/test/test_descr.py
>
> where there a working subclass of complex more in
> accordance with my intentions.
>
> class color_complex(complex):
> def __new__(cls,*args,**kws):
> result = complex.__new__(cls, *args)
> result.color = kws.get('color', 'BLUE')
> return result
>
>>>> a=color_complex(1,7,color='BLUE')
>>>> print a
> (1+7j)
>>>> print a.color
> BLUE
>
> which is very good.
>
> But on the chance that I end up pursuing this road, it would be good if
> I understood what I just did. It would certainly help with my
> documentation ;)
>
> Assistance appreciated.
>
> NOTE:
>
> The importance of the asset of the depth and breadth of Python archives
> - for learning (and teaching) and real world production - should not be
> underestimated, IMO. I could be confident if there was an answer to
> getting the functionality I was looking for as above, it would be found
> easily enough by a google search. It is only with the major
> technologies that one can hope to pose a question of almost any kind to
> google and get the kind of relevant hits one gets when doing a Python
> related search. Python is certainly a major technology, in that
> respect. As these archives serve as an extension to the documentation,
> the body of Python documentation is beyond any normal expectation.
>
> True, this asset is generally better for answers than explanations.
>
> I got the answer I needed. Pursuing here some explanation of that answer.
>
> Art
>
>
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