I understand from @shoyer that inheriting from DataArray may not be the best approach to extend DataArray with other specific methods but this was working before the latest release, and it is not working anymore. Just wondering if this would be some issue caused by new internal structure of DataArray, or maybe something I'm doing wrong?

For example, the code below works using xray.0.6.1:

``` import numpy as np

import xarray as xr #xarray.0.7.0

import xray as xr #xray.0.6.1

class NewArray(xr.DataArray): def init(self, darray): super(NewArray, self).init(darray, name='spec')

data = np.random.randint(0,10,12).reshape(4,3) x = [10,20,30] y = [1,2,3,4]

darray = xr.DataArray(data, coords={'y': y, 'x': x}, dims=['y','x']) narray = NewArray(darray)

print 'xr version: %s\n' % xr.version print 'DataArray object:\n%s\n' % darray print 'NewArray object:\n%s' % narray ```

but it does not work anymore when using the new xarray release. The NewArray instance is actually created, but if I try to access this object, or its narray.coords attribute, I get the traceback below. I can however access some other attributes from narray such as narray.values or narray.dims.

```

TypeError Traceback (most recent call last) /source/pymsl/pymsl/core/tests/inherit_test.py in <module>() 16 print 'xr version: %s\n' % xr.version 17 print 'DataArray object:\n%s\n' % darray ---> 18 print 'NewArray object:\n%s' % narray

/usr/local/lib/python2.7/site-packages/xarray/core/common.pyc in repr(self) 76 77 def repr(self): ---> 78 return formatting.array_repr(self) 79 80 def _iter(self):

/usr/local/lib/python2.7/site-packages/xarray/core/formatting.pyc in array_repr(arr) 254 if hasattr(arr, 'coords'): 255 if arr.coords: --> 256 summary.append(repr(arr.coords)) 257 258 if arr.attrs:

/usr/local/lib/python2.7/site-packages/xarray/core/coordinates.pyc in repr(self) 64 65 def repr(self): ---> 66 return formatting.coords_repr(self) 67 68 @property

/usr/local/lib/python2.7/site-packages/xarray/core/formatting.pyc in _mapping_repr(mapping, title, summarizer, col_width) 208 summary = ['%s:' % title] 209 if mapping: --> 210 summary += [summarizer(k, v, col_width) for k, v in mapping.items()] 211 else: 212 summary += [EMPTY_REPR]

/usr/local/Cellar/python/2.7.10_2/Frameworks/Python.framework/Versions/2.7/lib/python2.7/_abcoll.pyc in items(self) 412 def items(self): 413 "D.items() -> list of D's (key, value) pairs, as 2-tuples" --> 414 return [(key, self[key]) for key in self] 415 416 def values(self):

/usr/local/lib/python2.7/site-packages/xarray/core/coordinates.pyc in getitem(self, key) 44 key.split('.')[0] in self._names)): 45 # allow indexing current coordinates or components ---> 46 return self._data[key] 47 else: 48 raise KeyError(key)

/usr/local/lib/python2.7/site-packages/xarray/core/dataarray.pyc in getitem(self, key) 395 _, key, var = _get_virtual_variable(self._coords, key) 396 --> 397 return self._replace_maybe_drop_dims(var, name=key) 398 else: 399 # orthogonal array indexing

/usr/local/lib/python2.7/site-packages/xarray/core/dataarray.pyc in _replace_maybe_drop_dims(self, variable, name) 234 coords = OrderedDict((k, v) for k, v in self._coords.items() 235 if set(v.dims) <= allowed_dims) --> 236 return self._replace(variable, coords, name) 237 238 __this_array = _ThisArray()

/usr/local/lib/python2.7/site-packages/xarray/core/dataarray.pyc in _replace(self, variable, coords, name) 225 if name is self.__default: 226 name = self.name --> 227 return type(self)(variable, coords, name=name, fastpath=True) 228 229 def _replace_maybe_drop_dims(self, variable, name=__default):

TypeError: init() takes exactly 2 arguments (5 given) ```