From 599104c16a3b4503be2597bd797f7772a9043592 Mon Sep 17 00:00:00 2001
From: Vinnie Falco <vinnie.falco@gmail.com>
Date: Sat, 2 Feb 2019 10:20:38 -0800
Subject: [PATCH] async_echo supports move-only handlers

fix #1420
---
 CHANGELOG.md                |  1 +
 example/echo-op/echo_op.cpp | 21 ++++++++++++++-------
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 748fe1cf..cd90f994 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 Version 209:
 
 * Faster http::string_to_field
+* async_echo supports move-only handlers
 
 --------------------------------------------------------------------------------
 
diff --git a/example/echo-op/echo_op.cpp b/example/echo-op/echo_op.cpp
index 363df50c..bbe12c16 100644
--- a/example/echo-op/echo_op.cpp
+++ b/example/echo-op/echo_op.cpp
@@ -277,7 +277,7 @@ async_echo(AsyncStream& stream, CompletionToken&& token)
         BOOST_ASIO_HANDLER_TYPE(
             CompletionToken, void(boost::beast::error_code))>{
                 stream,
-                init.completion_handler}(boost::beast::error_code{}, 0);
+                std::move(init.completion_handler)}({}, 0);
 
     // This hook lets the caller see a return value when appropriate.
     // For example this might return std::future<error_code> if
@@ -289,6 +289,18 @@ async_echo(AsyncStream& stream, CompletionToken&& token)
 
 //]
 
+struct move_only_handler
+{
+    move_only_handler(move_only_handler&&) = default;
+    move_only_handler(move_only_handler const&) = delete;
+
+    void operator()(boost::beast::error_code ec)
+    {
+        if(ec)
+            std::cerr << ": " << ec.message() << std::endl;
+    }
+};
+
 int main(int argc, char** argv)
 {
     if(argc != 3)
@@ -317,12 +329,7 @@ int main(int argc, char** argv)
     acceptor.bind(ep);
     acceptor.listen();
     acceptor.accept(sock);
-    async_echo(sock,
-        [&](boost::beast::error_code ec)
-        {
-            if(ec)
-                std::cerr << argv[0] << ": " << ec.message() << std::endl;
-        });
+    async_echo(sock, move_only_handler{});
     ioc.run();
     return EXIT_SUCCESS;
 }