PyObject_GetItem() raises a KeyError if the key is not found in a mapping. In some cases it should be treated as any other error, but in other cases it should be caught and suppressed. The repeating pattern of PyObject_GetItem() followed by PyErr_ExceptionMatches(PyExc_KeyError) and PyErr_Clear() occurs 7 times in Python/bytecodes.c and at least 5 times in other files.
I propose to add private helper _PyMapping_LookupItem() which combines these three calls to make the code clearer. It also has a special case for exact dict, so eliminates even more repeating code. For example:
PyObject *m;
- if (PyDict_CheckExact(modules)) {
- m = Py_XNewRef(PyDict_GetItemWithError(modules, name));
- }
- else {
- m = PyObject_GetItem(modules, name);
- if (_PyErr_ExceptionMatches(tstate, PyExc_KeyError)) {
- _PyErr_Clear(tstate);
- }
- }
- if (_PyErr_Occurred(tstate)) {
+ if (_PyMapping_LookupItem(modules, name, &m) < 0) {
return NULL;
}The interface of _PyMapping_LookupItem() is very similar to other private helper _PyObject_LookupAttr() (see #76752) and to a proposed new C API for PyDict (see #106004).
Linked PRs
PyObject_GetItem()raises a KeyError if the key is not found in a mapping. In some cases it should be treated as any other error, but in other cases it should be caught and suppressed. The repeating pattern ofPyObject_GetItem()followed byPyErr_ExceptionMatches(PyExc_KeyError)andPyErr_Clear()occurs 7 times inPython/bytecodes.cand at least 5 times in other files.I propose to add private helper
_PyMapping_LookupItem()which combines these three calls to make the code clearer. It also has a special case for exact dict, so eliminates even more repeating code. For example:The interface of
_PyMapping_LookupItem()is very similar to other private helper_PyObject_LookupAttr()(see #76752) and to a proposed new C API for PyDict (see #106004).Linked PRs