(De-Duplication) linking validate hatch from hatch module

lib/matplotlib/hatch.py

@@ -2,8 +2,8 @@
 
 import numpy as np
 
-from matplotlib import _api
 from matplotlib.path import Path
+from matplotlib.rcsetup import validate_hatch
 
 
 class HatchPatternBase:
@@ -179,21 +179,7 @@ def __init__(self, hatch, density):
     ]
 
 
-def _validate_hatch_pattern(hatch):
-    valid_hatch_patterns = set(r'-+|/\xXoO.*')
-    if hatch is not None:
-        invalids = set(hatch).difference(valid_hatch_patterns)
-        if invalids:
-            valid = ''.join(sorted(valid_hatch_patterns))
-            invalids = ''.join(sorted(invalids))
-            _api.warn_deprecated(
-                '3.4',
-                removal='3.9',  # one release after custom hatches (#20690)
-                message=f'hatch must consist of a string of "{valid}" or '
-                        'None, but found the following invalid values '
-                        f'"{invalids}". Passing invalid values is deprecated '
-                        'since %(since)s and will become an error %(removal)s.'
-            )
+_validate_hatch_pattern = validate_hatch
 
 
 def get_path(hatchpattern, density=6):

lib/matplotlib/rcsetup.py

@@ -623,13 +623,14 @@ def validate_hatch(s):
     A hatch pattern string can have any sequence of the following
     characters: ``\ / | - + * . x o O``.
     """
-    if not isinstance(s, str):
-        raise ValueError("Hatch pattern must be a string")
-    _api.check_isinstance(str, hatch_pattern=s)
-    unknown = set(s) - {'\\', '/', '|', '-', '+', '*', '.', 'x', 'o', 'O'}
-    if unknown:
-        raise ValueError("Unknown hatch symbol(s): %s" % list(unknown))
-    return s
+    if s is not None:
+        if not isinstance(s, str):
+            raise ValueError("Hatch pattern must be a string")
+        _api.check_isinstance(str, hatch_pattern=s)
+        unknown = set(s) - {'\\', '/', '|', '-', '+', '*', '.', 'x', 'X', 'o', 'O'}
+        if unknown:
+            raise ValueError("Unknown hatch symbol(s): %s" % list(unknown))
+        return s
 
 
 validate_hatchlist = _listify_validator(validate_hatch)

lib/matplotlib/tests/test_rcparams.py

@@ -311,8 +311,7 @@ def generate_validator_testcases(valid):
          'success': (('--|', '--|'), ('\\oO', '\\oO'),
                      ('/+*/.x', '/+*/.x'), ('', '')),
          'fail': (('--_', ValueError),
-                  (8, ValueError),
-                  ('X', ValueError)),
+                  (8, ValueError)),
          },
         {'validator': validate_colorlist,
          'success': (('r,g,b', ['r', 'g', 'b']),