From 6695df5e782876957669cabe6d9b58102b1c7bf8 Mon Sep 17 00:00:00 2001
From: Tamino Huxohl <thuxohl@techfak.uni-bielefeld.de>
Date: Wed, 18 Dec 2024 15:25:38 +0100
Subject: [PATCH] implement compute method similar do depends_on

---
 widget_state/__init__.py |  3 ++-
 widget_state/util.py     | 18 +++++++++++++++++-
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/widget_state/__init__.py b/widget_state/__init__.py
index f468bf6..c6f7c49 100644
--- a/widget_state/__init__.py
+++ b/widget_state/__init__.py
@@ -18,7 +18,7 @@
 from .list_state import ListState
 from .state import State
 from .types import Serializable, Primitive
-from .util import computed_state
+from .util import computed_state, compute
 
 __all__ = [
     "BASIC_STATE_DICT",
@@ -36,4 +36,5 @@
     "Primitive",
     "computed_state",
     "computed",
+    "compute",
 ]
diff --git a/widget_state/util.py b/widget_state/util.py
index 4dd7b08..26cd7ef 100644
--- a/widget_state/util.py
+++ b/widget_state/util.py
@@ -7,7 +7,7 @@
 
 from __future__ import annotations
 
-from typing import Any, Callable, ParamSpec, TypeVar
+from typing import Any, Callable, Iterable, ParamSpec, TypeVar
 
 from .basic_state import BasicState
 from .state import State
@@ -15,6 +15,8 @@
 T = TypeVar("T", bound=BasicState[Any])
 P = ParamSpec("P")
 
+S = TypeVar("S", bound=State)
+
 
 def computed_state(
     func: Callable[P, T],
@@ -64,3 +66,17 @@ def _on_change(_: Any) -> None:
         return computed_value
 
     return wrapped
+
+
+def compute(
+    states: Iterable[State],
+    compute_value: Callable[[], S],
+    kwargs: dict[State, dict[str, Any]] = {},
+) -> S:
+    res = compute_value()
+
+    for state in states:
+        _kwargs = {} if state not in kwargs else kwargs[state]
+        state.on_change(lambda _: res.copy_from(compute_value()), **_kwargs)
+
+    return res