Merge pull request matplotlib#20311 from anntzer/rcs

FIX: Warn if a non-str is passed to an rcParam requiring a str.

Author: tacaswell

doc/api/next_api_changes/deprecations/20311-AL.rst

@@ -0,0 +1,5 @@
+rcParams will no longer cast inputs to str
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+After a deprecation period, rcParams that expect a (non-pathlike) str will no
+longer cast non-str inputs using `str`.  This will avoid confusing errors in
+subsequent code if e.g. a list input gets implicitly cast to a str.

lib/matplotlib/rcsetup.py

@@ -17,6 +17,7 @@
 from functools import lru_cache, reduce
 from numbers import Number
 import operator
+import os
 import re
 
 import numpy as np
@@ -198,6 +199,11 @@ def validator(s):
         if (allow_none and
                 (s is None or isinstance(s, str) and s.lower() == "none")):
             return None
+        if cls is str and not isinstance(s, str):
+            _api.warn_deprecated(
+                "3.5", message="Support for setting an rcParam that expects a "
+                "str value to a non-str value is deprecated since %(since)s "
+                "and support will be removed %(removal)s.")
         try:
             return cls(s)
         except (TypeError, ValueError) as e:
@@ -224,6 +230,15 @@ def validator(s):
     validate_float, doc='return a list of floats')
 
 
+def _validate_pathlike(s):
+    if isinstance(s, (str, os.PathLike)):
+        # Store value as str because savefig.directory needs to distinguish
+        # between "" (cwd) and "." (cwd, but gets updated by user selections).
+        return os.fsdecode(s)
+    else:
+        return validate_string(s)  # Emit deprecation warning.
+
+
 def validate_fonttype(s):
     """
     Confirm that this is a Postscript or PDF font type that we know how to
@@ -1154,7 +1169,7 @@ def _convert_validator_spec(key, conv):
     "savefig.bbox":         validate_bbox,  # "tight", or "standard" (= None)
     "savefig.pad_inches":   validate_float,
     # default directory in savefig dialog box
-    "savefig.directory":    validate_string,
+    "savefig.directory":    _validate_pathlike,
     "savefig.transparent":  validate_bool,
 
     "tk.window_focus": validate_bool,  # Maintain shell focus for TkAgg
@@ -1224,15 +1239,15 @@ def _convert_validator_spec(key, conv):
     # Additional arguments for HTML writer
     "animation.html_args":    validate_stringlist,
     # Path to ffmpeg binary. If just binary name, subprocess uses $PATH.
-    "animation.ffmpeg_path":  validate_string,
+    "animation.ffmpeg_path":  _validate_pathlike,
     # Additional arguments for ffmpeg movie writer (using pipes)
     "animation.ffmpeg_args":  validate_stringlist,
     # Path to AVConv binary. If just binary name, subprocess uses $PATH.
-    "animation.avconv_path":  validate_string,
+    "animation.avconv_path":  _validate_pathlike,
     # Additional arguments for avconv movie writer (using pipes)
     "animation.avconv_args":  validate_stringlist,
      # Path to convert binary. If just binary name, subprocess uses $PATH.
-    "animation.convert_path": validate_string,
+    "animation.convert_path": _validate_pathlike,
      # Additional arguments for convert movie writer (using pipes)
     "animation.convert_args": validate_stringlist,
 

lib/matplotlib/tests/test_rcparams.py

@@ -225,11 +225,11 @@ def generate_validator_testcases(valid):
                      (('a', 'b'), ['a', 'b']),
                      (iter(['a', 'b']), ['a', 'b']),
                      (np.array(['a', 'b']), ['a', 'b']),
-                     ((1, 2), ['1', '2']),
-                     (np.array([1, 2]), ['1', '2']),
                      ),
          'fail': ((set(), ValueError),
                   (1, ValueError),
+                  ((1, 2), _api.MatplotlibDeprecationWarning),
+                  (np.array([1, 2]), _api.MatplotlibDeprecationWarning),
                   )
          },
         {'validator': _listify_validator(validate_int, n=2),