add config_of function

in the file config_assign.cpp/hpp, it can be use similar to boost's boost::assign for config object.
I don't use it that much, but i found it useful especialy to pass or return a config that just contains one or two childs.

src/CMakeLists.txt

@@ -694,6 +694,7 @@ set(wesnoth-main_SRC
 	callable_objects.cpp
 	commandline_options.cpp
 	config_cache.cpp
+	config_assign.cpp
 	controller_base.cpp
 	desktop_util.cpp
 	dialogs.cpp

src/SConscript

@@ -73,6 +73,7 @@ libwesnoth_sources = Split("""
     pathfind/astarsearch.cpp
     builder.cpp
     clipboard.cpp
+	config_assign.cpp
     construct_dialog.cpp
     cursor.cpp
     display.cpp

src/config_assign.cpp

@@ -0,0 +1,92 @@
+/*
+   Part of the Battle for Wesnoth Project http://www.wesnoth.org/
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY.
+
+   See the COPYING file for more details.
+*/
+#include "config_assign.hpp"
+#include "config.hpp"
+
+
+config_of::config_of(const std::string& attrname, bool value)
+{
+	this->operator()(attrname, value);
+}
+
+config_of::config_of(const std::string& attrname, int value)
+{
+	this->operator()(attrname, value);
+}
+
+config_of::config_of(const std::string& attrname, unsigned int value)
+{
+	this->operator()(attrname, value);
+}
+
+config_of::config_of(const std::string& attrname, double value)
+{
+	this->operator()(attrname, value);
+}
+
+config_of::config_of(const std::string& attrname, const std::string& value)
+{
+	this->operator()(attrname, value);
+}
+config_of::config_of(const std::string& attrname, config::attribute_value value)
+{
+	this->operator()(attrname, value);
+}
+
+config_of::config_of(const std::string& tagname, const config& child)
+{
+	this->operator()(tagname, child);
+}
+
+config_of& config_of::operator()(const std::string& attrname, bool value)
+{
+	data_[attrname] = value;
+	return *this;
+}
+config_of& config_of::operator()(const std::string& attrname, int value)
+{
+	data_[attrname] = value;
+	return *this;
+}
+
+config_of& config_of::operator()(const std::string& attrname, unsigned  int value)
+{
+	data_[attrname] = value;
+	return *this;
+}
+config_of& config_of::operator()(const std::string& attrname, double value)
+{
+	data_[attrname] = value;
+	return *this;
+}
+config_of& config_of::operator()(const std::string& attrname, const std::string& value)
+{
+	data_[attrname] = value;
+	return *this;
+}
+config_of& config_of::operator()(const std::string& attrname, config::attribute_value value)
+{
+	data_[attrname] = value;
+	return *this;
+}
+
+config_of& config_of::operator()(const std::string& tagname, const config& child)
+{
+	data_.add_child(tagname, child);
+	return *this;
+}
+
+config_of::operator config() const
+{
+	return data_;
+}

src/config_assign.hpp

@@ -0,0 +1,41 @@
+/*
+   Part of the Battle for Wesnoth Project http://www.wesnoth.org/
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY.
+
+   See the COPYING file for more details.
+*/
+#ifndef CONFIG_ASSIGN_H_INCLUDED
+#define CONFIG_ASSIGN_H_INCLUDED
+
+#include <string>
+#include "config.hpp"
+
+class config_of
+{
+public:
+	config_of(const std::string& attrname, int value);
+	config_of(const std::string& attrname, unsigned int value);
+	config_of(const std::string& attrname, bool value);
+	config_of(const std::string& attrname, double value);
+	config_of(const std::string& attrname, const std::string& value);
+	config_of(const std::string& attrname, config::attribute_value value);
+	config_of(const std::string& tagname, const config& child);
+
+	config_of& operator()(const std::string& attrname, int value);
+	config_of& operator()(const std::string& attrname, unsigned int value);
+	config_of& operator()(const std::string& attrname, bool value);
+	config_of& operator()(const std::string& attrname, double value);
+	config_of& operator()(const std::string& attrname, const std::string& value);
+	config_of& operator()(const std::string& attrname, config::attribute_value value);
+	config_of& operator()(const std::string& tagname, const config& child);
+	operator config() const;
+private:
+	config data_;
+};
+#endif