- <span class="identifier">basic_socket</span><span class="special"><</span> <span class="identifier">protocol_type</span><span class="special">,</span> <span class="identifier">SocketService</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">peer</span><span class="special">,</span>
- <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span> <span class="special">&</span> <span class="identifier">ec</span><span class="special">);</span>
+ <span class="identifier">basic_socket</span><span class="special"><</span> <span class="identifier">Protocol1</span><span class="special">,</span> <span class="identifier">SocketService</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">peer</span><span class="special">,</span>
+ <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span> <span class="special">&</span> <span class="identifier">ec</span><span class="special">,</span>
+ <span class="keyword">typename</span> <span class="identifier">enable_if</span><span class="special"><</span> <span class="identifier">is_convertible</span><span class="special"><</span> <span class="identifier">Protocol</span><span class="special">,</span> <span class="identifier">Protocol1</span> <span class="special">>::</span><span class="identifier">value</span> <span class="special">>::</span><span class="identifier">type</span> <span class="special">*</span> <span class="special">=</span> <span class="number">0</span><span class="special">);</span>