REF: amend cache_states to decorators

python/rateslib/curves/curves.py

@@ -32,8 +32,8 @@
     _clear_cache_post,
     _new_state_post,
     _validate_states,
-    _WithState,
     _WithCache,
+    _WithState,
 )
 from rateslib.rs import Modifier, index_left_f64
 from rateslib.rs import from_json as from_json_rs
@@ -57,7 +57,7 @@
 # Contact rateslib at gmail.com if this code is observed outside its intended sphere.
 
 
-class Curve(_WithState, _WithCache):
+class Curve(_WithState, _WithCache[datetime, DualTypes]):
     """
     Curve based on DF parametrisation at given node dates with interpolation.
 

python/rateslib/fx_volatility.py

@@ -34,8 +34,8 @@
 from rateslib.mutability import (
     _clear_cache_post,
     _new_state_post,
-    _WithState,
     _WithCache,
+    _WithState,
 )
 from rateslib.rs import index_left_f64
 from rateslib.splines import PPSplineDual, PPSplineDual2, PPSplineF64, evaluate
@@ -46,7 +46,7 @@
 TERMINAL_DATE = dt(2100, 1, 1)
 
 
-class FXDeltaVolSmile(_WithState, _WithCache):
+class FXDeltaVolSmile(_WithState, _WithCache[float, DualTypes]):
     r"""
     Create an *FX Volatility Smile* at a given expiry indexed by delta percent.
 
@@ -774,7 +774,7 @@ def update_node(self, key: float, value: DualTypes) -> None:
     # Serialization
 
 
-class FXDeltaVolSurface(_WithState, _WithCache):
+class FXDeltaVolSurface(_WithState, _WithCache[datetime, FXDeltaVolSmile]):
     r"""
     Create an *FX Volatility Surface* parametrised by cross-sectional *Smiles* at different
     expiries.

python/rateslib/mutability/__init__.py

@@ -3,7 +3,7 @@
 import os
 from collections import OrderedDict
 from collections.abc import Callable
-from typing import ParamSpec, TypeVar, Generic
+from typing import ParamSpec, TypeVar
 
 from rateslib import defaults
 
@@ -56,7 +56,7 @@ def wrapper(*args: P.args, **kwargs: P.kwargs) -> R:
     return wrapper
 
 
-class _WithState[KT, VT]:
+class _WithState:
     """
     Record and manage the `state_id` of mutable classes.
 
@@ -70,8 +70,6 @@ class _WithState[KT, VT]:
 
     _state: int = 0
     _mutable_by_association = False
-    _cache: OrderedDict[KT, VT]
-    _cache_len: int
 
     def _set_new_state(self) -> None:
         """Set the state_id of a superclass. Some objects which are 'mutable by association'
@@ -95,6 +93,9 @@ def _get_composited_state(self) -> int:
 
 class _WithCache[KT, VT]:
 
+    _cache: OrderedDict[KT, VT]
+    _cache_len: int
+
     def _cached_value(self, key: KT, val: VT) -> VT:
         """Used to add a value to the cache and control memory size when returning some
         parameter from an object using cache and state management."""