Make ParticleFile store and create_new_zarrfile attrs read only

Author: VeckoTheGecko

parcels/particlefile.py

@@ -78,12 +78,12 @@ def __init__(self, store, outputdt, chunks=None, create_new_zarrfile=True):
         self._maxids = 0
         self._pids_written = {}
         self.metadata = {}
-        self.create_new_zarrfile = create_new_zarrfile
+        self._create_new_zarrfile = create_new_zarrfile
 
-        if isinstance(store, zarr.storage.Store):
-            self.store = store
-        else:
-            self.store = _get_store_from_pathlike(store)
+        if not isinstance(store, zarr.storage.Store):
+            store = _get_store_from_pathlike(store)
+
+        self._store = store
 
         # TODO v4: Enable once updating to zarr v3
         # if store.read_only:
@@ -118,6 +118,14 @@ def outputdt(self):
     def chunks(self):
         return self._chunks
 
+    @property
+    def store(self):
+        return self._store
+
+    @property
+    def create_new_zarrfile(self):
+        return self._create_new_zarrfile
+
     def _convert_varout_name(self, var):
         if var == "depth":
             return "z"
@@ -223,7 +231,7 @@ def _write_particle_data(self, *, particle_data, pclass, time_interval, time, in
                     ds[varout] = xr.DataArray(data=data, dims=dims, attrs=attrs[var.name])
                     ds[varout].encoding["chunks"] = self.chunks[0] if var.to_write == "once" else self.chunks  # type: ignore[index]
             ds.to_zarr(store, mode="w")
-            self.create_new_zarrfile = False
+            self._create_new_zarrfile = False
         else:
             Z = zarr.group(store=store, overwrite=False)
             obs = particle_data["obs_written"][indices_to_write]

tests/v4/test_particlefile.py

@@ -405,6 +405,13 @@ def test_particlefile_init(tmp_store):
     ParticleFile(tmp_store, outputdt=np.timedelta64(1, "s"), chunks=(1, 3))
 
 
+@pytest.mark.parametrize("name", ["store", "outputdt", "chunks", "create_new_zarrfile"])
+def test_particlefile_readonly_attrs(tmp_store, name):
+    pfile = ParticleFile(tmp_store, outputdt=np.timedelta64(1, "s"), chunks=(1, 3))
+    with pytest.raises(AttributeError, match="property .* of 'ParticleFile' object has no setter"):
+        setattr(pfile, name, "something")
+
+
 def test_particlefile_init_invalid(tmp_store):  # TODO: Add test for read only store
     with pytest.raises(ValueError, match="chunks must be a tuple"):
         ParticleFile(tmp_store, outputdt=np.timedelta64(1, "s"), chunks=1)