From 2c32713cf7d2722f5df1b99cf5c005c00b1d1916 Mon Sep 17 00:00:00 2001
From: Corentin Cadiou <corentin.cadiou@cphyc.me>
Date: Mon, 6 Nov 2023 15:41:48 +0000
Subject: [PATCH] oct_handler should be a read-only property

---
 yt/data_objects/index_subobjects/octree_subset.py | 9 +++++----
 yt/frontends/art/data_structures.py               | 6 +++++-
 yt/frontends/artio/data_structures.py             | 6 +++++-
 yt/frontends/ramses/data_structures.py            | 5 ++++-
 yt/frontends/stream/data_structures.py            | 6 +-----
 5 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/yt/data_objects/index_subobjects/octree_subset.py b/yt/data_objects/index_subobjects/octree_subset.py
index a74f5dc24f8..eb08750b9d7 100644
--- a/yt/data_objects/index_subobjects/octree_subset.py
+++ b/yt/data_objects/index_subobjects/octree_subset.py
@@ -1,3 +1,4 @@
+import abc
 from contextlib import contextmanager
 from functools import cached_property
 from itertools import product, repeat
@@ -33,7 +34,7 @@ def cc_cache_func(self, dobj):
     return cc_cache_func
 
 
-class OctreeSubset(YTSelectionContainer):
+class OctreeSubset(YTSelectionContainer, abc.ABC):
     _spatial = True
     _num_ghost_zones = 0
     _type_name = "octree_subset"
@@ -57,10 +58,10 @@ def __init__(self, base_region, domain, ds, num_zones=2, num_ghost_zones=0):
         self.base_selector = base_region.selector
 
     @property
+    @abc.abstractmethod
     def oct_handler(self):
-        # Use an indirection so that oct_handler
-        # doesn't have to exist when we create the subset
-        return self.domain.oct_handler
+        # In charge of returning the oct_handler
+        pass
 
     def __getitem__(self, key):
         tr = super().__getitem__(key)
diff --git a/yt/frontends/art/data_structures.py b/yt/frontends/art/data_structures.py
index 5c5281cc1b1..a901f780e3b 100644
--- a/yt/frontends/art/data_structures.py
+++ b/yt/frontends/art/data_structures.py
@@ -798,7 +798,11 @@ def __init__(self, ds, nvar, oct_handler, domain_id):
         self._level_count = None
         self._level_oct_offsets = None
         self._level_child_offsets = None
-        self.oct_handler = oct_handler
+        self._oct_handler = oct_handler
+
+    @property
+    def oct_handler(self):
+        return self._oct_handler
 
     @property
     def level_count(self):
diff --git a/yt/frontends/artio/data_structures.py b/yt/frontends/artio/data_structures.py
index 45052f01552..c220c5f82be 100644
--- a/yt/frontends/artio/data_structures.py
+++ b/yt/frontends/artio/data_structures.py
@@ -34,7 +34,7 @@ def __init__(self, base_region, sfc_start, sfc_end, oct_handler, ds):
         self.field_parameters = {}
         self.sfc_start = sfc_start
         self.sfc_end = sfc_end
-        self.oct_handler = oct_handler
+        self._oct_handler = oct_handler
         self.ds = ds
         self._last_mask = None
         self._last_selector_id = None
@@ -43,6 +43,10 @@ def __init__(self, base_region, sfc_start, sfc_end, oct_handler, ds):
         self.base_region = base_region
         self.base_selector = base_region.selector
 
+    @property
+    def oct_handler(self):
+        return self._oct_handler
+
     @property
     def min_ind(self):
         return self.sfc_start
diff --git a/yt/frontends/ramses/data_structures.py b/yt/frontends/ramses/data_structures.py
index abed7c157c2..96b7b389aa1 100644
--- a/yt/frontends/ramses/data_structures.py
+++ b/yt/frontends/ramses/data_structures.py
@@ -223,7 +223,6 @@ def __init__(self, ds, domain_id):
                 "Detected particle type %s in domain_id=%s", ph.ptype, domain_id
             )
             ph.read_header()
-            # self._add_ptype(ph.ptype)
 
     def __repr__(self):
         return "RAMSESDomainFile: %i" % self.domain_id
@@ -385,6 +384,10 @@ def __init__(
                 "of ghost zones, was called with num_ghost_zones=%s" % num_ghost_zones
             )
 
+    @property
+    def oct_handler(self):
+        return self.domain.oct_handler
+
     def _fill_no_ghostzones(self, fd, fields, selector, file_handler):
         ndim = self.ds.dimensionality
         # Here we get a copy of the file, which we skip through and read the
diff --git a/yt/frontends/stream/data_structures.py b/yt/frontends/stream/data_structures.py
index 4cc8b58354c..e6302649375 100644
--- a/yt/frontends/stream/data_structures.py
+++ b/yt/frontends/stream/data_structures.py
@@ -766,7 +766,7 @@ def __init__(self, base_region, ds, oct_handler, num_zones=2, num_ghost_zones=0)
         self.field_data = YTFieldData()
         self.field_parameters = {}
         self.ds = ds
-        self.oct_handler = oct_handler
+        self._oct_handler = oct_handler
         self._last_mask = None
         self._last_selector_id = None
         self._current_particle_type = "io"
@@ -788,10 +788,6 @@ def __init__(self, base_region, ds, oct_handler, num_zones=2, num_ghost_zones=0)
     def oct_handler(self):
         return self._oct_handler
 
-    @oct_handler.setter
-    def oct_handler(self, oh):
-        self._oct_handler = oh
-
     def retrieve_ghost_zones(self, ngz, fields, smoothed=False):
         try:
             new_subset = self._subset_with_gz