From 33ca05a3cb59d64a362a2d3a9e78501752b3c79c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan=20Hamal=20Dvo=C5=99=C3=A1k?= <mordae@anilinux.org>
Date: Tue, 11 Mar 2025 16:28:18 +0100
Subject: [PATCH] Deal with errors inside Computed
---
lazy_player/reactive.py | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/lazy_player/reactive.py b/lazy_player/reactive.py
index aa3c5e9..aae3b70 100644
--- a/lazy_player/reactive.py
+++ b/lazy_player/reactive.py
@@ -1,19 +1,23 @@
from __future__ import annotations
+import sys
+import traceback
from contextvars import ContextVar
from typing import Any, Callable, ClassVar, Generic, Self, TypeVar
from weakref import WeakSet
-__all__ = ["Ref", "Computed", "update_all_computed"]
+__all__ = ["Ref", "Computed", "Watcher", "update_all_computed"]
T = TypeVar("T")
class Ref(Generic[T]):
+ _error: Exception | None
_users: WeakSet[Computed[Any]]
_value: T
def __init__(self, initial: T):
+ self._error = None
self._value = initial
self._users = WeakSet()
@@ -24,6 +28,9 @@ class Ref(Generic[T]):
if computed is not None:
self._users.add(computed)
+ if self._error is not None:
+ raise self._error
+
return self._value
@value.setter
@@ -47,6 +54,7 @@ class Computed(Ref[T]):
_update: Callable[[], T]
def __init__(self, update: Callable[[], T]):
+ self._error = None
self._update = update
self._users = WeakSet()
self.update()
@@ -56,6 +64,10 @@ class Computed(Ref[T]):
try:
self.value = self._update()
+ self._error = None
+ except Exception as err:
+ self._error = err
+ traceback.print_exception(err, file=sys.stderr)
finally:
self._stack.reset(token)