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A read handler must meet the requirements for a handler.
A value h of a read handler class should work correctly in the
expression h(ec, s), where ec is an lvalue of type
const error_code and s is an lvalue of type const
size_t.
A free function as a read handler:
void read_handler(
const asio::error_code& ec,
std::size_t bytes_transferred)
{
...
}
A read handler function object:
struct read_handler
{
...
void operator()(
const asio::error_code& ec,
std::size_t bytes_transferred)
{
...
}
...
};
A lambda as a read handler:
socket.async_read(...
[](const asio::error_code& ec,
std::size_t bytes_transferred)
{
...
});
A non-static class member function adapted to a read handler using std::bind():
void my_class::read_handler(
const asio::error_code& ec,
std::size_t bytes_transferred)
{
...
}
...
socket.async_read(...,
std::bind(&my_class::read_handler,
this, std::placeholders::_1,
std::placeholders::_2));
A non-static class member function adapted to a read handler using boost::bind():
void my_class::read_handler(
const asio::error_code& ec,
std::size_t bytes_transferred)
{
...
}
...
socket.async_read(...,
boost::bind(&my_class::read_handler,
this, asio::placeholders::error,
asio::placeholders::bytes_transferred));