From 989452b26efef7d8644e6dc4db8486fd5972f997 Mon Sep 17 00:00:00 2001
From: Shizuo Fujita <fujita@clear-code.com>
Date: Wed, 21 Oct 2026 13:38:58 +0900
Subject: [PATCH] Document that Loop.new raises RuntimeError when no backend is
 usable

PR #119 made Loop.new raise RuntimeError instead of crashing when no
selected backend is usable. The documentation did not mention it, or
that $LIBEV_FLAGS can cause it unless :skip_environment is true.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 lib/cool.io/loop.rb | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/cool.io/loop.rb b/lib/cool.io/loop.rb
index 1d5ff99..bf17571 100644
--- a/lib/cool.io/loop.rb
+++ b/lib/cool.io/loop.rb
@@ -38,6 +38,10 @@ def self.default
     #     :kqueue (BSD/Mac OS X)
     #     :port   (Solaris 10)
     #
+    # Raises RuntimeError if none of the selected backends is usable.
+    # Unless :skip_environment is true, $LIBEV_FLAGS can override the
+    # backend selection and cause the same error.
+    #
     def initialize(options = {})
       @watchers = {}
       @active_watchers = 0