bpo-42128: Add __match_args__ to structseq-based classes by pablogsal · Pull Request #24732 · python/cpython

python

@@ -15,6 +15,7 @@ static const char visible_length_key[] = "n_sequence_fields"; static const char real_length_key[] = "n_fields"; static const char unnamed_fields_key[] = "n_unnamed_fields"; static const char match_args_key[] = "__match_args__";
/* Fields with this name have only a field index, not a field name. They are only allowed for indices < n_visible_fields. */ @@ -399,7 +400,40 @@ initialize_structseq_dict(PyStructSequence_Desc *desc, PyObject* dict, SET_DICT_FROM_SIZE(visible_length_key, desc->n_in_sequence); SET_DICT_FROM_SIZE(real_length_key, n_members); SET_DICT_FROM_SIZE(unnamed_fields_key, n_unnamed_members);
// Prepare and set __match_args__ Py_ssize_t i, k; PyObject* keys = PyTuple_New(desc->n_in_sequence); if (keys == NULL) { return -1; }
for (i = k = 0; i < desc->n_in_sequence; ++i) { if (desc->fields[i].name == PyStructSequence_UnnamedField) {

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I don't think we can handle this in a better way: just exclude them from match_args. The other (much worse option IMHO) is generate some missing names for these.

continue; } PyObject* new_member = PyUnicode_FromString(desc->fields[i].name); if (new_member == NULL) { goto error; } PyTuple_SET_ITEM(keys, k, new_member); k++; }
if (_PyTuple_Resize(&keys, k) == -1) { goto error; }
if (PyDict_SetItemString(dict, match_args_key, keys) < 0) { goto error; }
Py_DECREF(keys); return 0;
error: Py_DECREF(keys); return -1; }
static void