Subclassing hidden class

[Jp Calderone]

On Sun, Feb 16, 2003 at 09:11:06PM +0000, John Smith wrote:
> Is there a quick way to subclass that usually use a constructor function to
> return objects?
> For example,
> 
> >>> import numarray
> >>> class myarray(numarray.array):
>  pass
> 
> Traceback (most recent call last):
>   File "<pyshell#36>", line 1, in ?
>     class myarray(numarray.array):
> TypeError: cannot create 'function' instances


>>> import numarray
>>> numarray.array
<function array at 0x82691ec>
>>> numarray.array(0)
array(0)
>>> type(array(0))
<class 'numarray.NumArray'>
>>> numarray.NumArray
<class 'numarray.NumArray'>
>>> class Foo(numarray.NumArray): pass
... 
>>> Foo(0) # Uh oh!
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  File "/usr/local/lib/python2.2/site-packages/numarray/numarray.py", line
581, in __repr__
    MAX_LINE_WIDTH, PRECISION, SUPPRESS_SMALL, ', ', 1)
  File "/usr/local/lib/python2.2/site-packages/numarray/arrayprint.py", line
165, in array2string
    typeless = _stdtype(a._type)
  File "/usr/local/lib/python2.2/site-packages/numarray/arrayprint.py", line
149, in _stdtype
    return t in [numarray.Long, numarray.Float, numarray.Complex]
  File "/usr/local/lib/python2.2/site-packages/numarray/numerictypes.py",
line 102, in __cmp__
    return genericTypeRank.index(self.name) -
genericTypeRank.index(other.name)
ValueError: list.index(x): x not in list

  I guess this isn't very helpful, except in a very general sort of way for
looking more deeply into function/type/object relations.

  Jp

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