python · encukou · Feb 14, 2025 · Jul 31, 2019 · Feb 14, 2025
diff --git a/Doc/c-api/unicode.rst b/Doc/c-api/unicode.rst
@@ -256,13 +256,8 @@ the Python configuration.
 
 .. c:function:: int Py_UNICODE_ISPRINTABLE(Py_UCS4 ch)
 
-   Return ``1`` or ``0`` depending on whether *ch* is a printable character.
-   Nonprintable characters are those characters defined in the Unicode character
-   database as "Other" or "Separator", excepting the ASCII space (0x20) which is
-   considered printable.  (Note that printable characters in this context are
-   those which should not be escaped when :func:`repr` is invoked on a string.
-   It has no bearing on the handling of strings written to :data:`sys.stdout` or
-   :data:`sys.stderr`.)
+   Return ``1`` or ``0`` depending on whether *ch* is a printable character,
+   in the sense of :meth:`str.isprintable`.
 
 
 These APIs can be used for fast direct character conversions:

diff --git a/Doc/library/stdtypes.rst b/Doc/library/stdtypes.rst
@@ -2012,13 +2012,19 @@ expression support in the :mod:`re` module).
 
 .. method:: str.isprintable()
 
-   Return ``True`` if all characters in the string are printable or the string is
-   empty, ``False`` otherwise.  Nonprintable characters are those characters defined
-   in the Unicode character database as "Other" or "Separator", excepting the
-   ASCII space (0x20) which is considered printable.  (Note that printable
-   characters in this context are those which should not be escaped when
-   :func:`repr` is invoked on a string.  It has no bearing on the handling of
-   strings written to :data:`sys.stdout` or :data:`sys.stderr`.)
+   Return true if all characters in the string are printable, false if it
+   contains at least one non-printable character.
+
+   Here "printable" means the character is suitable for :func:`repr` to use in
+   its output; "non-printable" means that :func:`repr` on built-in types will
+   hex-escape the character.  It has no bearing on the handling of strings
+   written to :data:`sys.stdout` or :data:`sys.stderr`.
+
+   The printable characters are those which in the Unicode character database
+   (see :mod:`unicodedata`) have a general category in group Letter, Mark,
+   Number, Punctuation, or Symbol (L, M, N, P, or S); plus the ASCII space 0x20.
+   Nonprintable characters are those in group Separator or Other (Z or C),
+   except the ASCII space.
 
 
 .. method:: str.isspace()

diff --git a/Lib/test/test_str.py b/Lib/test/test_str.py
@@ -853,6 +853,15 @@ def test_isprintable(self):
         self.assertTrue('\U0001F46F'.isprintable())
         self.assertFalse('\U000E0020'.isprintable())
 
+    @support.requires_resource('cpu')
+    def test_isprintable_invariant(self):
+        for codepoint in range(sys.maxunicode + 1):
+            char = chr(codepoint)
+            category = unicodedata.category(char)
+            self.assertEqual(char.isprintable(),
+                             category[0] not in ('C', 'Z')
+                             or char == ' ')
+
     def test_surrogates(self):
         for s in ('a\uD800b\uDFFF', 'a\uDFFFb\uD800',
                   'a\uD800b\uDFFFa', 'a\uDFFFb\uD800a'):

diff --git a/Objects/clinic/unicodeobject.c.h b/Objects/clinic/unicodeobject.c.h
diff --git a/Objects/unicodectype.c b/Objects/unicodectype.c
@@ -142,18 +142,10 @@ int _PyUnicode_IsNumeric(Py_UCS4 ch)
     return (ctype->flags & NUMERIC_MASK) != 0;
 }
 
-/* Returns 1 for Unicode characters to be hex-escaped when repr()ed,
-   0 otherwise.
-   All characters except those characters defined in the Unicode character
-   database as following categories are considered printable.
-      * Cc (Other, Control)
-      * Cf (Other, Format)
-      * Cs (Other, Surrogate)
-      * Co (Other, Private Use)
-      * Cn (Other, Not Assigned)
-      * Zl Separator, Line ('\u2028', LINE SEPARATOR)
-      * Zp Separator, Paragraph ('\u2029', PARAGRAPH SEPARATOR)
-      * Zs (Separator, Space) other than ASCII space('\x20').
+/* Returns 1 for Unicode characters that repr() may use in its output,
+   and 0 for characters to be hex-escaped.
+
+   See documentation of `str.isprintable` for details.
 */
 int _PyUnicode_IsPrintable(Py_UCS4 ch)
 {

diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
@@ -12452,15 +12452,14 @@ unicode_isidentifier_impl(PyObject *self)
 /*[clinic input]
 str.isprintable as unicode_isprintable
 
-Return True if the string is printable, False otherwise.
+Return True if all characters in the string are printable, False otherwise.
 
-A string is printable if all of its characters are considered printable in
-repr() or if it is empty.
+A character is printable if repr() may use it in its output.
 [clinic start generated code]*/
 
 static PyObject *
 unicode_isprintable_impl(PyObject *self)
-/*[clinic end generated code: output=3ab9626cd32dd1a0 input=98a0e1c2c1813209]*/
+/*[clinic end generated code: output=3ab9626cd32dd1a0 input=4e56bcc6b06ca18c]*/
 {
     Py_ssize_t i, length;
     int kind;