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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* 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 3 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; 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 program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#ifndef ULTIMA4_CORE_OBSERVER_H
#define ULTIMA4_CORE_OBSERVER_H
namespace Ultima {
namespace Ultima4 {
template<class O, class A>
class Observable;
class NoArg;
/**
* This is the interface a class must implement to watch an
* Observable.
*/
template<class O, class A = NoArg *>
class Observer {
public:
virtual void update(O observable, A arg) = 0;
virtual ~Observer() {}
};
/**
* A specialized observer for watching observables that don't use the
* "arg" parameter to update.
*/
template<class O>
class Observer<O, NoArg *> {
public:
virtual void update(O observable, NoArg *arg) {
update(observable);
}
virtual void update(O observable) = 0;
virtual ~Observer() {}
};
/**
* Just an empty marker class to identify observers that take no args
* on update.
*/
class NoArg {
};
} // End of namespace Ultima4
} // End of namespace Ultima
#endif
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