MNT: re-instate respecting datapath in matplotlibrc file

tacaswell · tacaswell · commit ecd95c49a38b · 2020-03-16T18:28:24.000-04:00
Closes #16678 This does a bit of jiggery-pokery to respect the datapath set in the users matplotlibrc. This is going to have an expedited deprecation cycle as we don't think end-users should be setting this rcparam.
diff --git a/lib/matplotlib/__init__.py b/lib/matplotlib/__init__.py
@@ -132,6 +132,7 @@
 import shutil
 import subprocess
 import tempfile
+import warnings
 
 # cbook must import matplotlib only within function
 # definitions, so it is safe to import from it here.
@@ -269,10 +270,10 @@ def func(): ...
     ret = None
 
     @functools.wraps(func)
-    def wrapper():
+    def wrapper(**kwargs):
         nonlocal called, ret
         if not called:
-            ret = func()
+            ret = func(**kwargs)
             called = True
             _log.debug(fmt, ret)
         return ret
@@ -620,9 +621,30 @@ def get_cachedir():
 
 
 @_logged_cached('matplotlib data path: %s')
-def get_data_path():
+def get_data_path(*, _from_rc=None):
     """Return the path to Matplotlib data."""
+    if _from_rc is not None:
+        cbook.warn_deprecated(
+            "3.2",
+            message=("Setting the datapath via matplotlibrc is "
+            "deprecated %(since)s and will be removed in %(removal)s. "
+            ""),
+            removal='3.3')
+        path = Path(_from_rc)
+        if path.is_dir():
+            defaultParams['datapath'][0] = str(path)
+            return str(path)
+        else:
+            warnings.warn(f"You passed datapath: {_from_rc!r} in your "
+                          f"matplotribrc file ({matplotlib_fname()}). "
+                          "However this path does not exist, falling back "
+                          "to standard paths.")
+
+    return _get_data_path()
 
+
+@_logged_cached('(private) matplotlib data path: %s')
+def _get_data_path():
     if 'MATPLOTLIBDATA' in os.environ:
         path = os.environ['MATPLOTLIBDATA']
         if not os.path.isdir(path):
@@ -704,7 +726,7 @@ def gen_candidates():
             yield matplotlibrc
             yield os.path.join(matplotlibrc, 'matplotlibrc')
         yield os.path.join(get_configdir(), 'matplotlibrc')
-        yield os.path.join(get_data_path(), 'matplotlibrc')
+        yield os.path.join(_get_data_path(), 'matplotlibrc')
 
     for fname in gen_candidates():
         if os.path.exists(fname) and not os.path.isdir(fname):
@@ -972,7 +994,9 @@ def rc_params_from_file(fname, fail_on_error=False, use_default_template=True):
 
     with cbook._suppress_matplotlib_deprecation_warning():
         if config['datapath'] is None:
-            config['datapath'] = get_data_path()
+            config['datapath'] = _get_data_path()
+        else:
+            config['datapath'] = get_data_path(_from_rc=config['datapath'])
 
     if "".join(config['text.latex.preamble']):
         _log.info("""
