[PyROOT] Remove TClonesArray.__setitem__ pythonization

The `TClonesArray.__setitem__` pythonization was introduced in commit
67db9e5 with PR #3423.

However, this pythonization is quite unnatural, because a `TObjArray`
should not adopt external memory. In fact, on in the C++ side, all
`TObjArray`-inherited methods that take a `TObject *` and that would
adopt these objects are flagged as `MayNotUse` for good reasons!

Supporting this element setting only on the Python side therefore comes
with a very high cost of hacking deep into CPyCppyy, and the benefit of
this is not clear because the PR that introduced this feature didn't
refer to any user request.

Hence, this commit suggests to remove this pythonization, with the
ultimate goal of relying less on the usage of CPyCppyy internals.

bindings/pyroot/pythonizations/CMakeLists.txt

@@ -115,7 +115,6 @@ set(cpp_sources
     src/GenericPyz.cxx
     src/RVecPyz.cxx
     src/TClassPyz.cxx
-    src/TClonesArrayPyz.cxx
     src/TMemoryRegulator.cxx
     src/TObjectPyz.cxx
     src/TTreePyz.cxx

bindings/pyroot/pythonizations/python/ROOT/_pythonization/_tclonesarray.py

@@ -9,13 +9,18 @@
 ################################################################################
 
 from . import pythonization
-from libROOTPythonizations import AddSetItemTCAPyz
 
 
-@pythonization('TClonesArray')
+def _TClonesArray__setitem__(self, key, val):
+    raise RuntimeError(
+        "You can't set items of a TClonesArray! You can however TClonesArray::ConstructedAt() to access an element that is guaranteed to be constructed, and then modify it in-place."
+    )
+
+
+@pythonization("TClonesArray")
 def pythonize_tclonesarray(klass):
     # Parameters:
     # klass: class to be pythonized
 
     # Add item setter method
-    AddSetItemTCAPyz(klass)
+    klass.__setitem__ = _TClonesArray__setitem__

bindings/pyroot/pythonizations/src/PyROOTModule.cxx

@@ -51,8 +51,6 @@ static PyMethodDef gPyROOTMethods[] = {
     (char *)"Fully enable the use of TTree::SetBranchAddress from Python"},
    {(char *)"BranchPyz", (PyCFunction)PyROOT::BranchPyz, METH_VARARGS,
     (char *)"Fully enable the use of TTree::Branch from Python"},
-   {(char *)"AddSetItemTCAPyz", (PyCFunction)PyROOT::AddSetItemTCAPyz, METH_VARARGS,
-    (char *)"Customize the setting of an item of a TClonesArray"},
    {(char *)"AddPrettyPrintingPyz", (PyCFunction)PyROOT::AddPrettyPrintingPyz, METH_VARARGS,
     (char *)"Add pretty printing pythonization"},
    {(char *)"GetEndianess", (PyCFunction)PyROOT::GetEndianess, METH_NOARGS, (char *)"Get endianess of the system"},

bindings/pyroot/pythonizations/src/PyROOTPythonize.h

@@ -28,8 +28,6 @@ PyObject *AddTClassDynamicCastPyz(PyObject *self, PyObject *args);
 
 PyObject *AddTObjectEqNePyz(PyObject *self, PyObject *args);
 
-PyObject *AddSetItemTCAPyz(PyObject *self, PyObject *args);
-
 PyObject *AsRVec(PyObject *self, PyObject *obj);
 PyObject *AsRTensor(PyObject *self, PyObject *obj);
 

bindings/pyroot/pythonizations/test/CMakeLists.txt

@@ -73,9 +73,6 @@ ROOT_ADD_PYUNITTEST(pyroot_pyz_tseqcollection_listmethods tseqcollection_listmet
 # TIter pythonisations
 ROOT_ADD_PYUNITTEST(pyroot_pyz_titer_iterator titer_iterator.py)
 
-# TClonesArray pythonisations
-ROOT_ADD_PYUNITTEST(pyroot_pyz_tclonesarray_itemaccess tclonesarray_itemaccess.py)
-
 # TArray and subclasses pythonizations
 ROOT_ADD_PYUNITTEST(pyroot_pyz_tarray_len tarray_len.py)
 ROOT_ADD_PYUNITTEST(pyroot_pyz_tarray_getitem tarray_getitem.py)