id,node_id,number,title,user,state,locked,assignee,milestone,comments,created_at,updated_at,closed_at,author_association,active_lock_reason,draft,pull_request,body,reactions,performed_via_github_app,state_reason,repo,type
1379000408,I_kwDOAMm_X85SMeBY,7057,Hook for better control over copy behavior with duck-arrays?,12912489,open,0,,,0,2022-09-20T08:11:12Z,2022-09-20T08:12:22Z,,NONE,,,,"### Context

By using `copy(deep=False)` custom operations may avoid copying large amounts of data but can modify, e.g., coord dicts:

```python
tmp = da.copy(deep=False)
del tmp.coords['abc']
# Use tmp
```
When `da` wraps a duck-array with substructure the current implementation is insufficient:

```python
tmp = da.copy(deep=False)
# Imagine a duck-array similar to numpy.ma but with a dict of masks
del tmp.data.masks['abc']  # Bad: breaks `da`
# Use tmp
```


### Describe the solution you'd like

Currently there does not appear a solution to this, unless we know details about the duck array. Therefore, I wonder if we need an additional ""hook"" that duck-arrays may provide, which could be called by Xarray to make a non-deep copy?

```python
class MyDuckArray:
  def _copy_shallow_(self):  # TODO: better name
    """"""Copy everything except buffers""""""
```

```python
# in xarray.Variable
def copy(self, deep=True):
  if deep:
    data = copy.deepcopy(data)
  elif hasattr(data, '_copy_shallow_'):
   data = data._copy_shallow_()
```

### Additional context

This is the current implementation for `Variable`. There is no operation for `deep=False`:
https://github.com/pydata/xarray/blob/716973e41060184beebd64935afe196a805ef481/xarray/core/variable.py#L956-L957","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/7057/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,,13221727,issue