83 lines
2.2 KiB
Plaintext
83 lines
2.2 KiB
Plaintext
[/
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/ Copyright (c) 2003-2019 Christopher M. Kohlhoff (chris at kohlhoff dot com)
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/
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/ Distributed under the Boost Software License, Version 1.0. (See accompanying
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/ file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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/]
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[section:ResolveHandler Resolve handler requirements]
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A resolve handler must meet the requirements for a [link boost_asio.reference.Handler
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handler]. A value `h` of a resolve handler class should work correctly in the
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expression `h(ec, r)`, where `ec` is an lvalue of type `const error_code` and
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`r` is an lvalue of type `const ip::basic_resolver_results<InternetProtocol>`.
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`InternetProtocol` is the template parameter of the [link
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boost_asio.reference.ip__basic_resolver `ip::basic_resolver<>`] which is used to
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initiate the asynchronous operation.
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[heading Examples]
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A free function as a resolve handler:
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void resolve_handler(
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const boost::system::error_code& ec,
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boost::asio::ip::tcp::resolver::results_type results)
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{
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...
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}
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A resolve handler function object:
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struct resolve_handler
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{
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...
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void operator()(
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const boost::system::error_code& ec,
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boost::asio::ip::tcp::resolver::results_type results)
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{
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...
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}
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...
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};
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A lambda as a resolve handler:
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resolver.async_resolve(...,
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[](const boost::system::error_code& ec,
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boost::asio::ip::tcp::resolver::results_type results)
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{
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...
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});
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A non-static class member function adapted to a resolve handler using
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`std::bind()`:
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void my_class::resolve_handler(
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const boost::system::error_code& ec,
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boost::asio::ip::tcp::resolver::results_type results)
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{
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...
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}
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...
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resolver.async_resolve(...,
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std::bind(&my_class::resolve_handler,
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this, std::placeholders::_1,
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std::placeholders::_2));
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A non-static class member function adapted to a resolve handler using
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`boost::bind()`:
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void my_class::resolve_handler(
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const boost::system::error_code& ec,
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boost::asio::ip::tcp::resolver::results_type results)
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{
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...
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}
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...
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resolver.async_resolve(...,
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boost::bind(&my_class::resolve_handler,
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this, boost::asio::placeholders::error,
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boost::asio::placeholders::results));
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[endsect]
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