[Numpy-discussion] ndarray.fill and ma.array.filled

Fernando Perez Fernando.Perez at colorado.edu
Thu Mar 23 06:27:07 CST 2006

Tim Hochberg wrote:

> My opinion is that all methods and functions should either:
>     1. Always return a copy.
>     2. Always return a view
>     3. Return a view if possible otherwise raise an exception.

Well, but is copy/view the /only/ invariant worth guaranteeing?  I think there 
is a valid need for functions which ensure other invariants, such as 
contiguity.  There are applications (such as passing pointers to C/Fortran 
libraries which don't have striding mechanisms but will not modify their 
inputs) which require contiguous inputs, but where one would rather make a 
copy only if necessary.

My take on this is that we should /document/ clearly what invariants any given 
function satisfies, but I think the 'always view/always copy' view excludes an 
important usage case.  There may be others beyond contiguity, but that's the 
one that pops immediately to mind.



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