issue_comments: 282081462

Is it not? The documentation says it's new in numpy 1.11 and we're at 1.12 now.

I tried to make a small units-aware subclass of DataArray for myself. I managed to get the right behaviour for ufuncs (I think) but somehow my subclassed _binary_op is not getting called. I guess there is some logic somewhere that leads to replacing _binary_op in a subclass doesn't work (see below). But overall, how would you feel about an optional dependency on pint with a thin layer of code in the right place?

``` class UnitsAwareDataArray(xarray.DataArray): """Like xarray.DataArray, but transfers units """

def __array_wrap__(self, obj, context=None):
    new_var = super().__array_wrap__(obj, context)
    if self.attrs.get("units"):
        new_var.attrs["units"] = context[0](ureg(self.attrs.get("units"))).u
    return new_var

@staticmethod
def _binary_op(f, reflexive=False, join=None, **ignored_kwargs):
    # NB: http://stackoverflow.com/a/26807879/974555
    x = super(UnitsAwareDataArray, UnitsAwareDataArray)(f,
        reflexive, join, **ignored_kwargs)
    # do stuff
    return x

```