ChannelContentChange.h

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/*
 * Copyright (C) 2012 by
 *   MetraLabs GmbH (MLAB), GERMANY
 * and
 *   Neuroinformatics and Cognitive Robotics Labs (NICR) at TU Ilmenau, GERMANY
 * All rights reserved.
 *
 * Contact: info@mira-project.org
 *
 * Commercial Usage:
 *   Licensees holding valid commercial licenses may use this file in
 *   accordance with the commercial license agreement provided with the
 *   software or, alternatively, in accordance with the terms contained in
 *   a written agreement between you and MLAB or NICR.
 *
 * GNU General Public License Usage:
 *   Alternatively, this file may be used under the terms of the GNU
 *   General Public License version 3.0 as published by the Free Software
 *   Foundation and appearing in the file LICENSE.GPL3 included in the
 *   packaging of this file. Please review the following information to
 *   ensure the GNU General Public License version 3.0 requirements will be
 *   met: http://www.gnu.org/copyleft/gpl.html.
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 *
 * IN NO EVENT SHALL "MLAB" OR "NICR" BE LIABLE TO ANY PARTY FOR DIRECT,
 * INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF
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 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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 */

#ifndef _MIRA_CHANNELCONTENTCHANGE_H_
#define _MIRA_CHANNELCONTENTCHANGE_H_

#include <fw/ChannelReadWrite.h>
#include <fw/Framework.h>

namespace mira {


template <typename T>
class ChannelContentChange
{
public:
    Channel<T> subscribe(Authority& authority,
                         const std::string& channelID,
                         boost::function<void (ChannelRead<T>)> fn)
    {
        mFunction = fn;
        return authority.subscribe<T>(channelID, &ChannelContentChange<T>::callback, this);
    }

    template<typename Class>
    Channel<T> subscribe(Authority& authority,
                         const std::string& channelID,
                         void (Class::*f)(ChannelRead<T>), Class* obj)
    {
        return subscribe(authority, channelID, boost::bind(f, obj, _1));
    }

    void callback(ChannelRead<T> value)
    {
        if (!mLast || *mLast == value->value())
        mFunction(value);
        mLast = value->value();
    }

private:
    boost::function<void (ChannelRead<T>)> mFunction;
    boost::optional<T> mLast;
};


}

#endif