cursed: new package for UseState

Signed-off-by: Xe Iaso <me@xeiaso.net>

3 files changed, 59 insertions, 0 deletions

diff --git a/cursed/doc.go b/cursed/doc.go
new file mode 100644
index 0000000..b613846
--- /dev/null
+++ b/cursed/doc.go
@@ -0,0 +1,12 @@
+// Package cursed contains code that should never be used by anyone.
+//
+// This place is a message... and part of a system of messages... pay attention to it!
+// Sending this message was important to us. We considered ourselves to be a powerful culture.
+// This place is not a place of honor... no highly esteemed deed is commemorated here... nothing valued is here.
+// What is here was dangerous and repulsive to us. This message is a warning about danger.
+// The danger is in a particular location... it increases towards a center... the center of danger is here... of a particular size and shape, and below us.
+// The danger is still present, in your time, as it was in ours.
+// The danger is to the body, and it can kill.
+// The form of the danger is an emanation of energy.
+// The danger is unleashed only if you substantially disturb this place physically. This place is best shunned and left uninhabited.
+package cursed
diff --git a/cursed/useState.go b/cursed/useState.go
new file mode 100644
index 0000000..f5dcf0b
--- /dev/null
+++ b/cursed/useState.go
@@ -0,0 +1,31 @@
+package cursed
+
+import "sync"
+
+// UseState is a copy of the useState monad in React/Preact.
+//
+// This is a thread-safe stateful container that allows you to set
+// and get a shared value.
+//
+// Consumers should take care to NOT mutate any values in the fetched
+// variable.
+func UseState[T any](initial T) (func() T, func(T)) {
+	var (
+		lock sync.Mutex
+		data T = initial
+
+		set = func(upda T) {
+			lock.Lock()
+			defer lock.Unlock()
+			data = upda
+		}
+
+		get = func() T {
+			lock.Lock()
+			defer lock.Unlock()
+			return data
+		}
+	)
+
+	return get, set
+}
diff --git a/cursed/useState_test.go b/cursed/useState_test.go
new file mode 100644
index 0000000..6278034
--- /dev/null
+++ b/cursed/useState_test.go
@@ -0,0 +1,16 @@
+package cursed
+
+import "testing"
+
+func TestUseState(t *testing.T) {
+	val, setVal := UseState[string]("hi")
+
+	if val() != "hi" {
+		t.Errorf("wanted %q but got %q", "hi", val())
+	}
+
+	setVal("goodbye")
+	if val() != "goodbye" {
+		t.Errorf("wanted %q but got %q", "goodbye", val())
+	}
+}