8000 bpo-41842: Add codecs.unregister() function (GH-22360) · python/cpython@d332e7b · GitHub
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bpo-41842: Add codecs.unregister() function (GH-22360)
Add codecs.unregister() and PyCodec_Unregister() functions to unregister a codec search function.
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‎Doc/c-api/codec.rst

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@@ -10,6 +10,14 @@ Codec registry and support functions
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As side effect, this tries to load the :mod:`encodings` package, if not yet
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done, to make sure that it is always first in the list of search functions.
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.. c:function:: int PyCodec_Unregister(PyObject *search_function)
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Unregister a codec search function and clear the registry's cache.
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If the search function is not registered, do nothing.
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Return 0 on success. Raise an exception and return -1 on error.
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.. versionadded:: 3.10
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.. c:function:: int PyCodec_KnownEncoding(const char *encoding)
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Return ``1`` or ``0`` depending on whether there is a registered codec for

‎Doc/library/codecs.rst

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:class:`CodecInfo` object. In case a search function cannot find
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a given encoding, it should return ``None``.
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.. note::
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Search function registration is not currently reversible,
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which may cause problems in some cases, such as unit testing or
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module reloading.
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.. function:: unregister(search_function)
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Unregister a codec search function and clear the registry's cache.
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If the search function is not registered, do nothing.
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.. versionadded:: 3.10
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While the builtin :func:`open` and the associated :mod:`io` module are the
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recommended approach for working with encoded text files, this module

‎Doc/whatsnew/3.10.rst

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@@ -109,6 +109,12 @@ base64
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Add :func:`base64.b32hexencode` and :func:`base64.b32hexdecode` to support the
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Base32 Encoding with Extended Hex Alphabet.
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codecs
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------
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Add a :func:`codecs.unregister` function to unregister a codec search function.
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(Contributed by Hai Shi in :issue:`41842`.)
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curses
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------
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@@ -237,6 +243,10 @@ New Features
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:class:`datetime.time` objects.
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(Contributed by Zackery Spytz in :issue:`30155`.)
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* Add a :c:func:`PyCodec_Unregister` function to unregister a codec
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search function.
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(Contributed by Hai Shi in :issue:`41842`.)
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Porting to Python 3.10
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----------------------
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‎Include/codecs.h

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@@ -27,6 +27,14 @@ PyAPI_FUNC(int) PyCodec_Register(
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PyObject *search_function
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);
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/* Unregister a codec search function and clear the registry's cache.
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If the search function is not registered, do nothing.
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Return 0 on success. Raise an exception and return -1 on error. */
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PyAPI_FUNC(int) PyCodec_Unregister(
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PyObject *search_function
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);
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/* Codec registry lookup API.
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Looks up the given encoding and returns a CodecInfo object with

‎Lib/test/test_codecs.py

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@@ -1641,6 +1641,18 @@ def test_register(self):
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self.assertRaises(TypeError, codecs.register)
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self.assertRaises(TypeError, codecs.register, 42)
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def test_unregister(self):
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name = "nonexistent_codec_name"
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search_function = mock.Mock()
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codecs.register(search_function)
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self.assertRaises(TypeError, codecs.lookup, name)
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search_function.assert_called_with(name)
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search_function.reset_mock()
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codecs.unregister(search_function)
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self.assertRaises(LookupError, codecs.lookup, name)
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search_function.assert_not_called()
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def test_lookup(self):
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self.assertRaises(TypeError, codecs.lookup)
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self.assertRaises(LookupError, codecs.lookup, "__spam__")

‎Misc/ACKS

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@@ -1575,6 +1575,7 @@ Akash Shende
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Charlie Shepherd
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Bruce Sherwood
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Gregory Shevchenko
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Hai Shi
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Alexander Shigin
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Pete Shinners
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Michael Shiplett

‎Misc/NEWS.d/next/C API/2020-09-27-20-43-16.bpo-41842.bCakAj.rst

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Add :c:func:`PyCodec_Unregister` function to unregister a codec search
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function.

‎Misc/NEWS.d/next/Library/2020-09-23-22-52-24.bpo-41842.lIuhC9.rst

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Add :func:`codecs.unregister` function to unregister a codec search function.

‎Modules/_codecsmodule.c

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@@ -68,6 +68,27 @@ _codecs_register(PyObject *module, PyObject *search_function)
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Py_RETURN_NONE;
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}
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/*[clinic input]
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_codecs.unregister
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search_function: object
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/
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Unregister a codec search function and clear the registry's cache.
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If the search function is not registered, do nothing.
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[clinic start generated code]*/
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static PyObject *
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_codecs_unregister(PyObject *module, PyObject *search_function)
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/*[clinic end generated code: output=1f0edee9cf246399 input=dd7c004c652d345e]*/
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{
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if (PyCodec_Unregister(search_function) < 0) {
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return NULL;
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}
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Py_RETURN_NONE;
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}
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/*[clinic input]
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_codecs.lookup
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encoding: str
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static PyMethodDef _codecs_functions[] = {
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_CODECS_REGISTER_METHODDEF
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_CODECS_UNREGISTER_METHODDEF
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_CODECS_LOOKUP_METHODDEF
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_CODECS_ENCODE_METHODDEF
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_CODECS_DECODE_METHODDEF

‎Modules/clinic/_codecsmodule.c.h

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‎Python/codecs.c

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@@ -50,6 +50,31 @@ int PyCodec_Register(PyObject *search_function)
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return -1;
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}
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int
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PyCodec_Unregister(PyObject *search_function)
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{
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PyInterpreterState *interp = PyInterpreterState_Get();
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PyObject *codec_search_path = interp->codec_search_path;
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/* Do nothing if codec_search_path is not created yet or was cleared. */
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if (codec_search_path == NULL) {
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return 0;
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}
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assert(PyList_CheckExact(codec_search_path));
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Py_ssize_t n = PyList_GET_SIZE(codec_search_path);
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for (Py_ssize_t i = 0; i < n; i++) {
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PyObject *item = PyList_GET_ITEM(codec_search_path, i);
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if (item == search_function) {
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if (interp->codec_search_cache != NULL) {
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assert(PyDict_CheckExact(interp->codec_search_cache));
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PyDict_Clear(interp->codec_search_cache);
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}
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return PyList_SetSlice(codec_search_path, i, i+1, NULL);
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}
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}
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return 0;
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}
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extern int _Py_normalize_encoding(const char *, char *, size_t);
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/* Convert a string to a normalized Python string(decoded from UTF-8): all characters are

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