New submission from STINNER Victor <vstin...@python.org>:
In C, the following pattern (A) is very common:
Py_INCREF(sysdict);
interp->sysdict = sysdict;
* (1) Increment the reference counter
* (2) Store a reference to the object somewhere
Similar pattern (B) using return:
Py_INCREF(temp);
return temp;
The problem in these patterns is that the object has to be written twice. I
propose to add a simple new Py_NewRef() function which returns a new strong
reference. In short, it's just:
static inline PyObject* Py_NewRef(PyObject *obj)
{
Py_INCREF(obj);
return obj;
}
(The actual implementation is just a little bit more complex, to also export it
as a regular function.)
Pattern (A) becomes:
interp->sysdict = Py_NewRef(sysdict);
Pattern (B) becomes:
return Py_NewRef(temp);
Py_NewRef() might help to prepare a C extension to be converted to HPy which
uses a HPy_Dup() function. HPy_Dup() is different than "Py_INCREF(obj), obj"
for subtle reasons. I let you dig into HPy documentation for the rationale:
https://hpy.readthedocs.io/en/latest/api.html#handles
Even if you ignore HPy, Py_NewRef() avoids to repeat the object variable, and
so makes the code simpler. Simple example:
-#define Py_RETURN_NONE return Py_INCREF(Py_None), Py_None
+#define Py_RETURN_NONE return Py_NewRef(Py_None)
----------
components: C API
messages: 380337
nosy: vstinner
priority: normal
severity: normal
status: open
title: [C API] Add Py_NewRef() function to get a new strong reference to an
object
versions: Python 3.10
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue42262>
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