API: Raise AttributeError on closed HDFStore

Previously, we called _check_if_open, which would raise a ClosedFileError
whenever the desired attribute wasn't found. This prevented the check required
for PEP519 to work properly, since hasattr shouldn't raise that error.

Author: TomAugspurger

doc/source/whatsnew/v0.21.0.txt

@@ -40,6 +40,8 @@ Backwards incompatible API changes
 - Support has been dropped for Python 3.4 (:issue:`15251`)
 - The Categorical constructor no longer accepts a scalar for the ``categories`` keyword. (:issue:`16022`)
 
+- Accessing a non-existent attribute on a closed :class:`HDFStore` will now
+  raise an ``AttributeError`` rather than a ``ClosedFileError`` (:issue:`16301`)
 
 .. _whatsnew_0210.api:
 

pandas/io/pytables.py

@@ -472,7 +472,6 @@ def __delitem__(self, key):
 
     def __getattr__(self, name):
         """ allow attribute access to get stores """
-        self._check_if_open()
         try:
             return self.get(name)
         except:

pandas/tests/io/test_pytables.py

@@ -4453,7 +4453,7 @@ def f():
             pytest.raises(ClosedFileError, lambda: 'df' in store)
             pytest.raises(ClosedFileError, lambda: len(store))
             pytest.raises(ClosedFileError, lambda: store['df'])
-            pytest.raises(ClosedFileError, lambda: store.df)
+            pytest.raises(AttributeError, lambda: store.df)
             pytest.raises(ClosedFileError, store.select, 'df')
             pytest.raises(ClosedFileError, store.get, 'df')
             pytest.raises(ClosedFileError, store.append, 'df2', df)