html_url,issue_url,id,node_id,user,created_at,updated_at,author_association,body,reactions,performed_via_github_app,issue
https://github.com/pydata/xarray/issues/3829#issuecomment-597321847,https://api.github.com/repos/pydata/xarray/issues/3829,597321847,MDEyOklzc3VlQ29tbWVudDU5NzMyMTg0Nw==,14808389,2020-03-10T21:16:20Z,2020-03-10T23:19:20Z,MEMBER,":+1:

We might want to discourage using this to add methods to the `DataArray` / `Dataset` namespace, though.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,575564170
https://github.com/pydata/xarray/issues/3829#issuecomment-597286480,https://api.github.com/repos/pydata/xarray/issues/3829,597286480,MDEyOklzc3VlQ29tbWVudDU5NzI4NjQ4MA==,2443309,2020-03-10T20:02:31Z,2020-03-10T20:02:31Z,MEMBER,Would it be worth adding @keewis' examples to the accessor documentation? ,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,575564170
https://github.com/pydata/xarray/issues/3829#issuecomment-594682466,https://api.github.com/repos/pydata/xarray/issues/3829,594682466,MDEyOklzc3VlQ29tbWVudDU5NDY4MjQ2Ng==,7441788,2020-03-04T17:27:09Z,2020-03-04T17:27:09Z,CONTRIBUTOR,"@keewis, thanks for the suggestions. Both seem reasonable.

In your first example, if you wanted to prohibit `obj.weighted.sum(dim)`, you could just check for `self._weight` in `sum()`. Though I suppose it would be nice to be able to have the interpreter enforce the requirement and not have to do an explicit check in every method.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,575564170
https://github.com/pydata/xarray/issues/3829#issuecomment-594670062,https://api.github.com/repos/pydata/xarray/issues/3829,594670062,MDEyOklzc3VlQ29tbWVudDU5NDY3MDA2Mg==,14808389,2020-03-04T17:10:59Z,2020-03-04T17:15:52Z,MEMBER,"not sure if you really should use accessors to do that; having a function return a wrapper object might be enough.

Then again, an accessor is a slightly modified version of a property so you can just make your object callable by defining `__call__`:
```python
@xr.register_dataarray_accessor(""weighted"")
class Weighted:
    def __init__(self, xarray_obj):
        self._obj = xarray_obj
        self._weight = None

    def __call__(self, weight):
        self._weight = weight

    def sum(self, dim):
        return ""weighted sum""
```
this does allow calling `obj.weighted.sum(dim)`, so instead you can use:
```python
In [2]: class Weighted:
   ...:     def __init__(self, obj, weight): 
   ...:         self._obj = obj 
   ...:         self._weight = weight 
   ...:  
   ...:     def sum(self, dim): 
   ...:         return f""weighted sum over {dim} and with weight {self._weight}"" 
   ...:  
   ...: @xr.register_dataarray_accessor(""weighted"") 
   ...: def weighted(obj): 
   ...:     def wrapped(weight): 
   ...:         return Weighted(obj, weight) 
   ...:     return wrapped 
   ...:  
   ...: da = xr.DataArray(data=range(5), dims=""x"") 
   ...: da.weighted(5).sum(dim=""x"")
Out[2]: 'weighted sum over x and with weight 5'
```

Edit: the warning about a overridden attribute was the result of rerunning the code without restarting the interpreter","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,575564170