[Numpy-discussion] MA bug or feature?

[Pierre GM]

Michael,
I wonder whether the Mask class you suggest is not a bit overkill. There 
should be enough tools in the existing MA module to do what we want. And I 
don't wanna think about compatibility the number of changes in the MA code 
that'd be required (but I'm lazy)...

For the sake of consistency and optimization, I still think it could be easier 
(and cleaner) to make `nomask` the default for a MaskedArray without masked 
values. That could for example be implemented by forcing `nomask` at the 
creation of the MaskedArray with an extra 
`if mask and not mask.any(): mask=nomask`, or by using Paul's 
make_mask( flag=1) trick.

Masking some specific values could still be done when mask is nomask with an 
intermediary MA.getmaskarray() step.

On a side note, modifying an existing mask is a delicate matter. Everything's 
OK if you use masks as a way to hide existing data, it's more complex when 
initially you have some holes in your dataset...