up3

server/event/context.go

@@ -0,0 +1,28 @@
+package event
+
+// Context represents the context of an event. Handlers of an event may call methods on the context to change
+// the result of the event.
+type Context[T any] struct {
+	cancel bool
+	val    T
+}
+
+// C returns a new event context.
+func C[T any](v T) *Context[T] {
+	return &Context[T]{val: v}
+}
+
+// Val returns the subject of the Context.
+func (ctx *Context[T]) Val() T {
+	return ctx.val
+}
+
+// Cancelled returns whether the context has been cancelled.
+func (ctx *Context[T]) Cancelled() bool {
+	return ctx.cancel
+}
+
+// Cancel cancels the context.
+func (ctx *Context[T]) Cancel() {
+	ctx.cancel = true
+}

server/event/doc.go

@@ -0,0 +1,6 @@
+// Package event exposes a single exported `Context` type that may be used to influence the execution flow of events
+// that occur on a server.
+// Generally, the caller of `event.C()` calls `Context.Cancelled()` to check if the `Context` was cancelled (using
+// `Context.Cancel()`) by whatever code it was passed to.
+// who is then able to cancel it by calling `Context.Cancel()`.
+package event