Dynamically create Variables classes to avoid shared state (#413)

lumen/state.py

@@ -122,11 +122,11 @@ def spec(self, spec: Dict[str, Any]):
     def variables(self) -> Variables:
         from .variables import Variables
         if self._variable is None:
-            self._variable = Variables()
+            self._variable = Variables.create_variables()
         if pn.state.curdoc is None:
             return self._variable  # type: ignore
         elif pn.state.curdoc not in self._variables:
-            self._variables[pn.state.curdoc] = variables = Variables()
+            self._variables[pn.state.curdoc] = variables = Variables.create_variables()
             for var in self._variable._vars.values():  # type: ignore
                 variables.add_variable(var)
         return self._variables[pn.state.curdoc]

lumen/variables/base.py

@@ -33,6 +33,8 @@ class Variables(param.Parameterized):
     components to easily watch changes in a variable.
     """
 
+    _counter: ClassVar[int] = 0
+
     def __init__(self, **params):
         super().__init__(**params)
         self._vars = {}
@@ -41,9 +43,15 @@ def __init__(self, **params):
     def keys(self):
         return self._vars.keys()
 
+    @classmethod
+    def create_variables(cls):
+        new_cls = type(f'Variables{cls._counter}', (cls,), {})()
+        cls._counter += 1
+        return new_cls
+
     @classmethod
     def from_spec(cls, spec):
-        variables = cls()
+        variables = cls.create_variables()
         if pn.state.curdoc:
             state._variables[pn.state.curdoc] = variables
         for name, var_spec in spec.items():
@@ -134,6 +142,7 @@ def add_variable(self, var: 'Variable' | _PnWidget | param.Parameter) -> 'Variab
             variable.param.unwatch(self._watchers.pop(var.name))
         self._vars[var.name] = var
         self.param.add_parameter(var.name, param.Parameter(default=var.value))
+        self.param.update(**{var.name: var.value})
         self._watchers[var.name] = var.param.watch(
             partial(self._update_value, var.name), 'value'
         )