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[C API] Add PyDict_ContainsString() function #108314
Description
Feature or enhancement
Has this already been discussed elsewhere?
No response given
Links to previous discussion of this feature:
No response
Proposal:
Most, if not all, PyDict C APIs have a "String" flavor where the key argument is expressed as a UTF-8 encoded bytes string. But the PyDict_Contains() API is missing such variant.
I suppose that it was not proposed before since PyDict_GetItemString(dict, key) != NULL can already be used. My problem is that PyDict_GetItemString() ignores errors: I would like to report errors.
The newly added PyDict_GetItemStringRef() can be used to check if a dictionary has a key and report errors, but it requires calling Py_DECREF() which is not convenient. Example:
PyObject *value;
if (PyDict_GetItemStringRef(dict, key, &value) < 0) {
// ... handle error ...
}
int has_value = (value != NULL);
Py_XDECREF(value);
// ... use has_value ...
I would like to be able to replace this code with:
int has_value = PyDict_ContainsString(dict, key);
if (has_value < 0) {
// ... handle error ...
}
// ... use has_value ...
There is no need to INCREF/DECREF just to check if a dictionary has a key.
Activity
pythongh-108314: Add PyDict_ContainsString() function
pythongh-108314: Add PyDict_ContainsString() function
pythongh-108314: Add PyDict_ContainsString() function
vstinner commentedon Aug 22, 2023
There is already an abstract PyMapping_HasKeyString() function. Sadly, on error, this function clears the exception and returns 0 :-(
corona10 commentedon Aug 23, 2023
FYI, there was the discussion with adding this API.
capi-workgroup/problems#23
encukou commentedon Aug 23, 2023
And here: #100100
pythongh-108314: Add PyDict_ContainsString() function
gh-108314: Add PyDict_ContainsString() function (#108323)
pythongh-108314: PyDict_GetItemString() mentions UTF-8
vstinner commentedon Aug 24, 2023
I added the function to pythoncapi-compat: python/pythoncapi-compat@4734c8e
[3.12] gh-108314: PyDict_GetItemString() mentions UTF-8 (#108448)
[3.12] pythongh-108314: PyDict_GetItemString() mentions UTF-8 (python…
[3.11] [3.12] gh-108314: PyDict_GetItemString() mentions UTF-8 (GH-10…