Question

So this is official Boost PropertyTree example, I try to compile it on my visual studio 2008 and same on VS2010 get Error C2228: left of '.put_value' must have class/struct/union c:\program files (x86)\boost-1.46.1\include\boost\property_tree\detail\ptree_implementation.hpp 795 1

Here is code I use:

#include <stdio.h>
#include <iostream>
#include <fstream>
#include <set>
#include <sstream>
#include <boost/foreach.hpp>
#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/xml_parser.hpp>

using namespace std;

std::string m_file;          // log filename
int m_level;                 // debug level
std::set<string> m_modules;  // modules where logging is enabled

// Loads debug_settings structure from the specified XML file
void load( std::ifstream &file)
{
    // Create an empty property tree object
    using boost::property_tree::ptree;
    ptree pt;

    // Load the XML file into the property tree. If reading fails
    // (cannot open file, parse error), an exception is thrown.
    read_xml(file, pt);

    // Get the filename and store it in the m_file variable.
    // Note that we construct the path to the value by separating
    // the individual keys with dots. If dots appear in the keys,
    // a path type with a different separator can be used.
    // If the debug.filename key is not found, an exception is thrown.
    m_file = pt.get<std::string>("debug.filename");

    // Get the debug level and store it in the m_level variable.
    // This is another version of the get method: if the value is
    // not found, the default value (specified by the second
    // parameter) is returned instead. The type of the value
    // extracted is determined by the type of the second parameter,
    // so we can simply write get(...) instead of get<int>(...).
    m_level = pt.get("debug.level", 0);

    // Iterate over the debug.modules section and store all found
    // modules in the m_modules set. The get_child() function
    // returns a reference to the child at the specified path; if
    // there is no such child, it throws. Property tree iterators
    // are models of BidirectionalIterator.
    BOOST_FOREACH(ptree::value_type &v,
        pt.get_child("debug.modules"))
        m_modules.insert(v.second.data());
}

// Saves the debug_settings structure to the specified XML file
void save(const std::string &filename)
{
    // Create an empty property tree object
    using boost::property_tree::ptree;
    ptree pt;

    // Put log filename in property tree
    pt.put("debug.filename", m_file);

    // Put debug level in property tree
    pt.put("debug.level", m_level);

    // Iterate over the modules in the set and put them in the
    // property tree. Note that the put function places the new
    // key at the end of the list of keys. This is fine most of
    // the time. If you want to place an item at some other place
    // (i.e. at the front or somewhere in the middle), this can
    // be achieved using a combination of the insert and put_own
    // functions.
    BOOST_FOREACH(const std::string &name, m_modules)
        pt.put("debug.modules.module", name, true);

    // Write the property tree to the XML file.
    write_xml(filename, pt);
}

int main()
{
    std::ifstream script( "<debug>\n   <filename>debug.log</filename>\n    <modules>\n        <module>Finance</module>\n       <module>Admin</module>\n        <module>HR</module>\n    </modules>\n    <level>2</level>\n</debug>\n");
    load(script);
    save("j.js");
    cout << "parse complete" << endl;
    cin.get();
}

I have not changed my boost distribution in any way but it does not compile. Why?

Answer 1

The sample code for 1.46.1 has changed:

http://www.boost.org/doc/libs/1_46_1/libs/property_tree/examples/debug_settings.cpp

The relevant change is

BOOST_FOREACH(const std::string &name, m_modules)
pt.add(“debug.modules.module”, name);