BUG: __getattr__ must raise AttributeError if name not found

lpsinger · lpsinger · commit f4d9e9cb7b47 · 2021-08-10T17:12:14.000-04:00
PR matplotlib#20733 added module-level `__getattr__` functions to several modules. All of the functions with the exception of the one in `matplotlib.style.core` had a terminal `raise AttributeError` to handle unmatched attributes. The omission in `matplotlib.style.core` was probably unintentional; it results in confusing and buggy behavior such as: ```pycon >>> import matplotlib.style.core >>> if hasattr(matplotlib.style.core, '__warningregistry__'): ... del matplotlib.style.core.__warningregistry__ ... Traceback (most recent call last): File "<stdin>", line 2, in <module> AttributeError: __warningregistry__ ``` This causes problems in the unit tests for astropy affiliated packages. See astropy/astropy#12038.
diff --git a/lib/matplotlib/style/core.py b/lib/matplotlib/style/core.py
@@ -33,6 +33,7 @@ def __getattr__(name):
     if name == "STYLE_FILE_PATTERN":
         _api.warn_deprecated("3.5", name=name)
         return re.compile(r'([\S]+).%s$' % STYLE_EXTENSION)
+    raise AttributeError(f"module {__name__!r} has no attribute {name!r}")
 
 
 BASE_LIBRARY_PATH = os.path.join(mpl.get_data_path(), 'stylelib')
