notifier.h

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//
//  Copyright (c) Benjamin Kaufmann 2010
//
//  This 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 file is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with this file; if not, write to the Free Software
//  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
//
// NOTE: ProgramOptions is inspired by Boost.Program_options
//       see: www.boost.org/libs/program_options
//
#ifndef PROGRAM_OPTIONS_NOTIFIER_H_INCLUDED
#define PROGRAM_OPTIONS_NOTIFIER_H_INCLUDED

namespace ProgramOptions { namespace detail {

// Notifier
// HACK:
// This should actually be replaced with a proper and typesafe delegate class.
// At least, it should be parametrized on the actual parameter type since
// the invocation of f via the generic func is not strictly conforming.
// Yet, it should work on all major compilers - we do not mess with
// the address and the alignment of void* should be compatible with that of T*.
template <class ParamT>
struct Notifier {
        typedef bool (*notify_func_type)(void*, const std::string& name, ParamT);
        Notifier() : obj(0), func(0) {}
        template <class O>
        Notifier(O* o, bool (*f)(O*, const std::string&, ParamT)) {
                obj = o;
                func= reinterpret_cast<notify_func_type>(f);
        }
        void*            obj;
        notify_func_type func;
        bool notify(const std::string& name, ParamT val) const {
                return func(obj, name, val);
        }
        bool empty() const { return func == 0; }
}; 

template <class ParamT, class ObjT>
struct Notify {
        typedef bool (*type)(ObjT*, const std::string& name, ParamT);
};

} }
#endif