如何使用提升解析 XML 中的 2 个以上级别

我从boost库中得到了这段代码。http://www.boost.org/doc/libs/1_42_0/doc/html/boost_propertytree/tutorial.html

这是他们拥有的 xml 文件

<debug>
    <filename>debug.log</filename>
    <modules>
        <module>Finance</module>
        <module>Admin</module>
        <module>HR</module>
    </modules>
    <level>2</level>
</debug>

加载这些值并打印它们的代码是

#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/xml_parser.hpp>
#include <boost/foreach.hpp>
#include <string>
#include <set>
#include <exception>
#include <iostream>
struct debug_settings
{
    std::string m_file;               // log filename
    int m_level;                      // debug level
    std::set<std::string> m_modules;  // modules where logging is enabled
    void load(const std::string &filename);
    void save(const std::string &filename);
};
void debug_settings::load(const std::string &filename)
{
    using boost::property_tree::ptree;
    ptree pt;
    read_xml(filename, pt);
    m_file = pt.get<std::string>("debug.filename");
    m_level = pt.get("debug.level", 0);
    BOOST_FOREACH(ptree::value_type &v, pt.get_child("debug.modules"))
    m_modules.insert(v.second.data());
}
void debug_settings::save(const std::string &filename)
{
    using boost::property_tree::ptree;
    ptree pt;
    pt.put("debug.filename", m_file);
    pt.put("debug.level", m_level);
    BOOST_FOREACH(const std::string &name, m_modules)
    pt.put("debug.modules.module", name,true);
    write_xml(filename, pt);
}
int main()
{
    try
    {
        debug_settings ds;
        ds.load("debug_settings.xml");
        ds.save("debug_settings_out.xml");
        std::cout << "Successn";
    }
    catch (std::exception &e)
    {
        std::cout << "Error: " << e.what() << "n";
    }
    return 0;
}

但它给了我一个错误

usr/include/boost/property_tree/detail/ptree_implementation.hpp：769：错误：请求"tr"中的成员"put_value"，该成员属于非类类型"bool"

谁能告诉我我错过了什么？