Sasha wrote:

> >>>b = array([1])
> >>>ndarray((5,), strides=(0,), buffer=b)
> >>>        
> >>>
> Traceback (most recent call last):
>   File "<stdin>", line 1, in ?
> TypeError: buffer is too small for requested array
> 
> I would think memory-saving is the only justification for allowing
> zero strides.
> 
> What use does your change enable?
>   
> 
I was just simplifying the PyArray_CheckStrides code. 
I didn't try to actually enable creating 0-stride arrays in 
PyArray_NewFromDescr.
I don't mind if it is enabled though.   I just haven't done it yet.

I agree that 0-stride arrays are a "can-of-worms", and I also do not see 
changing ufunc behavior.  The current behavior is understandable and 
exactly what one would expect with zero-stride and multiple dimensioned 
arrays.  

i.e.

b = arange(5);
b.strides = 0
add(b,1,b)

where b has shape (5,) and stride (0,) would add 1 to the first element 
of b 5 times.  Since all elements of the array b are obtained from the 
first element (that's what stride=0 means), you end up with an array of 
all 5's.   This may not be useful, I agree, but it is understandable and 
changing it would be too much of an exception.   If somebody is creating 
0-stride arrays on their own, then they must know what they are doing.

-Travis








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