[3.13] gh-48181: Document codecs.charmap_build (GH-135997) (#136124)

miss-islington · StanFromIreland · web-flow · commit ef4a70b63f31 · 2025-06-30T15:52:53.000+02:00
gh-48181: Document `codecs.charmap_build` (GH-135997) (cherry picked from commit 2bdd503) Co-authored-by: Stan Ulbrych <89152624+StanFromIreland@users.noreply.github.com>
diff --git a/Doc/library/codecs.rst b/Doc/library/codecs.rst
@@ -53,6 +53,14 @@ any codec:
    :exc:`UnicodeDecodeError`). Refer to :ref:`codec-base-classes` for more
    information on codec error handling.
 
+.. function:: charmap_build(string)
+
+   Return a mapping suitable for encoding with a custom single-byte encoding.
+   Given a :class:`str` *string* of up to 256 characters representing a
+   decoding table, returns either a compact internal mapping object
+   ``EncodingMap`` or a :class:`dictionary <dict>` mapping character ordinals
+   to byte values. Raises a :exc:`TypeError` on invalid input.
+
 The full details for each codec can also be looked up directly:
 
 .. function:: lookup(encoding)
