Avoiding data copies?

[dakoop]

@tacaswell brought up the possibility of mutating numpy arrays instead of having the input array disjoint from the output array. Potential ideas involve enforcing cardinality=1 on output ports, or having some way to inform VisTrails that such mutated objects exist so caching, etc. can deal with this.

[tacaswell]

attn @ericdill @giltis

[tacaswell]

I think the cardinality constraint is a bit nastier, the input port which takes in an object that it will mutate needs to enforce that the cardinality on the output port that it is connected to is 1.