dictlike behavior for components (#130)

basics for #117. maybe later we can use the dict proxy class in xattree instead of implementing it ourselves?

Author: wpbonelli

flopy4/mf6/component.py

@@ -1,10 +1,42 @@
 from abc import ABC
+from collections.abc import MutableMapping
+
+from xattree import xattree
 
 COMPONENTS = {}
 """MF6 component registry."""
 
 
-class Component(ABC):
+@xattree
+class Component(ABC, MutableMapping):
     @classmethod
     def __attrs_init_subclass__(cls):
         COMPONENTS[cls.__name__.lower()] = cls
+
+    def __attrs_post_init__(self):
+        self._where = type(self).__xattree__["where"]
+
+    def __getitem__(self, key):
+        data = getattr(self, self._where)
+        return data.children[key]
+
+    def __setitem__(self, key, value):
+        data = getattr(self, self._where)
+        if key in data.children:
+            data.update({key: value})
+        else:
+            data = data.assign({key: value})
+        setattr(self, self._where, data)
+
+    def __delitem__(self, key):
+        data = getattr(self, self._where)
+        data = data.drop_nodes(key)
+        setattr(self, self._where, data)
+
+    def __iter__(self):
+        data = getattr(self, self._where)
+        return iter(data.children)
+
+    def __len__(self):
+        data = getattr(self, self._where)
+        return len(data.children)

test/test_component.py

@@ -234,3 +234,9 @@ def test_init_big_sim():
         chd.head.data.todense(),
         sim.models["gwf"].chd[0].data.head.data.todense(),
     )
+
+    # test dictionary access/deletion
+    assert gwf.get("npf")
+    assert gwf["npf"].attrs["host"] is npf
+    del gwf["npf"]
+    assert not gwf.get("npf")