c++ - 错误 C2825 : 'F' : must be a class or namespace when followed by '::'

Question

我在分析代码错误的原因时遇到了一些麻烦。我的代码看起来很好，其他开发人员也说很好:

void handle_read_headers(const boost::system::error_code& err, RESTClient::response& resp)
{
    if (!err)
    {
        // Start reading remaining data until EOF.
        boost::asio::async_read(socket_, response_,
            boost::asio::transfer_at_least(1),
            boost::bind(&client::handle_read_content, this,
            boost::asio::placeholders::error,
            boost::asio::placeholders::bytes_transferred,
            boost::ref(resp)));

    }
}

void handle_read_content(const boost::system::error_code& ec, size_t bytes_transferred, RESTClient::response& resp)
{
    if (!ec)
    {
        // Write all of the data that has been read so far.
        std::cout << &response_;

        // Continue reading remaining data until EOF.
        boost::asio::async_read(socket_, response_,
            boost::asio::transfer_at_least(1),
            boost::bind(&client::handle_read_content, this,
            boost::asio::placeholders::error));
    }
}

完整的源代码可以在这里找到:http://bit.ly/1gnemqG

错误是这样的

Error   1   error C2825: 'F': must be a class or namespace when followed by '::'    C:\local\boost_1_58_0\boost\bind\bind.hpp   69  1   HttpClientDemo
Error   2   error C2039: 'result_type' : is not a member of '`global namespace''    C:\local\boost_1_58_0\boost\bind\bind.hpp   69  1   HttpClientDemo
Error   3   error C2146: syntax error : missing ';' before identifier 'type'    C:\local\boost_1_58_0\boost\bind\bind.hpp   69  1   HttpClientDemo
Error   4   error C2208: 'boost::_bi::type' : no members defined using this type    C:\local\boost_1_58_0\boost\bind\bind.hpp   69  1   HttpClientDemo
Error   5   error C1903: unable to recover from previous error(s); stopping compilation C:\local\boost_1_58_0\boost\bind\bind.hpp   69  1   HttpClientDemo

这段代码可能有什么问题？

Answer 1

在 client::handle_read_content 中，对 boost::bind 的调用缺少参数。它应该与 client::handle_read_headers 中的相同:

boost::asio::async_read(socket_, response_,
        boost::asio::transfer_at_least(1),
        boost::bind(&client::handle_read_content, this,
                    boost::asio::placeholders::error,
                    boost::asio::placeholders::bytes_transferred, // this line was missing 
                    boost::ref(resp) // this line was missing 
        )
);