del and state.delete() can delete state variables or attributes

Author: craigbarratt

custom_components/pyscript/eval.py

@@ -1221,7 +1221,7 @@ async def recurse_assign(self, lhs, val):
                 return
             if dot_count > 0:
                 raise NameError(
-                    f"invalid name '{var_name}' (should be 'domain.entity' or 'domain.entity.attr'"
+                    f"invalid name '{var_name}' (should be 'domain.entity' or 'domain.entity.attr')"
                 )
             if self.curr_func and var_name in self.curr_func.global_names:
                 self.global_sym_table[var_name] = val
@@ -1284,6 +1284,11 @@ async def ast_delete(self, arg):
                         del self.sym_table[arg1.id]
                 else:
                     raise NameError(f"name '{arg1.id}' is not defined")
+            elif isinstance(arg1, ast.Attribute):
+                var_name = await self.ast_attribute_collapse(arg1, check_undef=False)
+                if not isinstance(var_name, str):
+                    raise NameError("state name should be 'domain.entity' or 'domain.entity.attr'")
+                State.delete(var_name)
             else:
                 raise NotImplementedError(f"unknown target type {arg1} in del")
 

custom_components/pyscript/state.py

@@ -44,7 +44,7 @@ class State:
     # Last value of state variable notifications.  We maintain this
     # so that trigger evaluation can use the last notified value,
     # rather than fetching the current value, which is subject to
-    # race conditions when multiple state variables are set.
+    # race conditions when multiple state variables are set quickly.
     #
     notify_var_last = {}
 
@@ -307,6 +307,36 @@ async def service_call(*args, **kwargs):
                 f"state '{parts[0]}.{parts[1]}' has no attribute '{parts[2]}'"
             )
 
+    @classmethod
+    def delete(cls, var_name, context=None):
+        """Delete a state variable or attribute from hass."""
+        parts = var_name.split(".")
+        if not context:
+            context = Function.task2context.get(asyncio.current_task(), None)
+        context_arg = {"context": context} if context else {}
+        if len(parts) == 2:
+            if var_name in cls.notify_var_last or var_name in cls.notify:
+                #
+                # immediately update a variable we are monitoring since it could take a while
+                # for the state changed event to propagate
+                #
+                cls.notify_var_last[var_name] = None
+            if not cls.hass.states.async_remove(var_name, **context_arg):
+                raise NameError(f"name '{var_name}' not defined")
+            return
+        if len(parts) == 3:
+            var_name = f"{parts[0]}.{parts[1]}"
+            value = cls.hass.states.get(var_name)
+            if value is None:
+                raise NameError(f"state {var_name} doesn't exist")
+            new_attr = value.attributes.copy()
+            if parts[2] not in new_attr:
+                raise AttributeError(f"state '{var_name}' has no attribute '{parts[2]}'")
+            del new_attr[parts[2]]
+            cls.set(f"{var_name}", value.state, new_attributes=new_attr, **context_arg)
+            return
+        raise NameError(f"invalid name '{var_name}' (should be 'domain.entity' or 'domain.entity.attr')")
+
     @classmethod
     def getattr(cls, var_name):
         """Return a dict of attributes for a state variable."""
@@ -374,6 +404,7 @@ def register_functions(cls):
             "state.getattr": cls.getattr,
             "state.get_attr": cls.get_attr,  # deprecated form; to be removed
             "state.persist": cls.persist,
+            "state.delete": cls.delete,
             "pyscript.config": cls.pyscript_config,
         }
         Function.register(functions)

docs/new_features.rst

@@ -11,12 +11,13 @@ to work at any random time.
 The latest release is 1.0.0, released on November 9, 2020.  Here is the `stable documentation <https://hacs-pyscript.readthedocs.io/en/stable>`__
 for that release.
 
-Since that release, the master (head of tree) version in GitHub has several new features and bug fixes.
-Here is the master `latest documentation <https://hacs-pyscript.readthedocs.io/en/latest>`__.
+Over time, the master (head of tree) version in GitHub will include new features and bug fixes.
+Here is the master `latest documentation <https://hacs-pyscript.readthedocs.io/en/latest>`__
+if you want to see the new features or bug fixes.
 
 Planned new features post 1.0.0 include:
 
-- ``del`` can delete state variables and state variable attributes
+- support mqtt triggers (#98, #105)
 - use ``aionofity`` to auto-reload newly written script files, at least on linux (#74)
 - consider allowing native Python functions inside pyscript (#71)
 - consider implementing function decorators (#43)
@@ -28,15 +29,18 @@ Planned new features post 1.0.0 include:
 
 The new features since 1.0.0 in master include:
 
-- Added ``state_hold_false=None`` optional period in seconds to ``@state_trigger`` and ``task.wait_until()``.
+- Added ``state_hold_false=None`` optional period in seconds to ``@state_trigger()`` and ``task.wait_until()``.
   This requires the trigger expression to be ``False`` for at least that period (including 0) before a
-  successful trigger.  Proposed by @tchef69 (#89).
+  successful trigger. Setting this optional parameter makes state triggers edge triggered (ie,
+  triggers only on transition from ``False`` to ``True``), instead of the default level trigger (ie,
+  only has to evaluate to ``True``). Proposed by @tchef69 (#89).
+- ``del`` and new function ``state.delete()` can delete state variables and state variable attributes
 
 Bug fixes since 1.0.0 in master include:
 
 - state setting now copies the attributes, to avoid a strange ``MappingProxyType`` recursion error
   inside HASS, reported by @github392 (#87).
-- the deprecated function ``state.get_attr`` was missing an ``await``, which caused an exception; in 1.0.0 use
+- the deprecated function ``state.get_attr`` was missing an ``await``, which causes an exception; in 1.0.0 use
   ``state.getattr``, reported and fixed by @dlashua (#88).
 - the ``packaging`` module is installed if not found, since certain HASS configurations might not include it;
   fixed by @raman325 (#90, #91).

docs/reference.rst

@@ -710,6 +710,9 @@ where the state variable name is computed dynamically). These functions allow yo
 variable using its string name. The set function also allows you to optionally set the attributes,
 which you can’t do if you are directly assigning to the variable:
 
+``state.delete(name)``
+  Deletes the given state variable or attribute.  The Python ``del`` statement can also be used
+  to delete a state variable or attribute.
 ``state.get(name)``
   Returns the value of the state variable given its string ``name``. A ``NameError`` exception
   is thrown if the name doesn't exist. If ``name`` is a string of the form ``DOMAIN.entity.attr``

tests/test_unit_eval.py

@@ -145,6 +145,10 @@
 state.set("pyscript.var1", 200, attr3 = 'abc')
 chk.append([pyscript.var1.attr1, pyscript.var1.attr2, pyscript.var1.attr3])
 chk.append(state.getattr("pyscript.var1"))
+del pyscript.var1.attr3
+chk.append(state.getattr("pyscript.var1"))
+state.delete("pyscript.var1.attr2")
+chk.append(state.getattr("pyscript.var1"))
 state.set("pyscript.var1", pyscript.var1, {})
 chk.append(state.getattr("pyscript.var1"))
 state.set("pyscript.var1", pyscript.var1, new_attributes={"attr2": 8.5, "attr3": "xyz"})
@@ -166,6 +170,8 @@
             ["100xyz", 1, 3.5],
             [1, 3.5, "abc"],
             {"attr1": 1, "attr2": 3.5, "attr3": "abc"},
+            {"attr1": 1, "attr2": 3.5},
+            {"attr1": 1},
             {},
             {"attr2": 8.5, "attr3": "xyz"},
             {"attr2": "abc", "attr3": "xyz"},
@@ -963,6 +969,14 @@ async def test_eval(hass):
     ["f'xxx{'", "syntax error f-string: expecting '}' (test, line 1)"],
     ["f'xxx{foo() i}'", "syntax error invalid syntax (<fstring>, line 1)"],
     ["del xx", "Exception in test line 1 column 0: name 'xx' is not defined"],
+    [
+        "pyscript.var1 = 1; del pyscript.var1; pyscript.var1",
+        "Exception in test line 1 column 38: name 'pyscript.var1' is not defined",
+    ],
+    [
+        "pyscript.var1 = 1; state.delete('pyscript.var1'); pyscript.var1",
+        "Exception in test line 1 column 50: name 'pyscript.var1' is not defined",
+    ],
     ["return", "Exception in test line 1 column 0: return statement outside function"],
     ["break", "Exception in test line 1 column 0: break statement outside loop"],
     ["continue", "Exception in test line 1 column 0: continue statement outside loop"],