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[C API] Add Py_NewRef() function to get a new strong reference to an object #86428
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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)The problem in these patterns is that the object has to be written twice.
I'm talking about the variable name which has to be repeated (written twice) in the source code.
Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.
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