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Avoid boilerplate for traversing a mutable heap type #138342
Description
Throughout the codebase, instances of mutable heap types must always implement the GC protocol to traverse their type. This leads to the following being repeated a lot:
static int
object_visit(PyObject *op, visitproc visit, void *arg)
{
Py_VISIT(Py_TYPE(op));
return 0;
}To reduce code duplication, I think it would be beneficial to have a common helper for this case. I'm going to call this _PyObject_VisitType for now.
cc @picnixz
Activity
serhiy-storchaka commentedon Sep 1, 2025
When this boilerplate was added at first place, I suggested to do this automatically for each heap type with the Py_TPFLAGS_HAVE_GC flag. It belongs to the garbage collector (which does type-specific things in any case), no need to pollute the source code with
Py_VISIT(Py_TYPE(op)). For some reasons my suggestion was ignored.picnixz commentedon Sep 1, 2025
I think you were talking about #84398 right?
serhiy-storchaka commentedon Sep 1, 2025
Exactly. Now, after adding all these
Py_VISIT(Py_TYPE(op)), we cannot use that approach and are doomed to addPy_VISIT(Py_TYPE(op))in eachtp_traverse.gh-138342: Use a common utility for visiting an object's type (GH-138343
pythongh-138342: Use a common utility for visiting an object's type (p…
pythongh-138342: Move _PyObject_VisitType() to the internal C API
gh-138342: Move _PyObject_VisitType() to the internal C API (#139734)