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/*=========================================================================
Program: GDCM (Grassroots DICOM). A DICOM library
Copyright (c) 2006-2011 Mathieu Malaterre
All rights reserved.
See Copyright.txt or http://gdcm.sourceforge.net/Copyright.html for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notice for more information.
=========================================================================*/
#ifndef GDCMSUBJECT_H
#define GDCMSUBJECT_H
#include "gdcmObject.h"
namespace gdcm
{
class Event;
class Command;
class SubjectInternals;
/**
* \brief Subject
* \see Command Event
*/
class GDCM_EXPORT Subject : public Object
{
public:
Subject();
~Subject();
/** Allow people to add/remove/invoke observers (callbacks) to any GDCM
* object. This is an implementation of the subject/observer design
* pattern. An observer is added by specifying an event to respond to
* and an gdcm::Command to execute. It returns an unsigned long tag
* which can be used later to remove the event or retrieve the
* command. The memory for the Command becomes the responsibility of
* this object, so don't pass the same instance of a command to two
* different objects */
unsigned long AddObserver(const Event & event, Command *);
unsigned long AddObserver(const Event & event, Command *) const;
/** Get the command associated with the given tag. NOTE: This returns
* a pointer to a Command, but it is safe to asign this to a
* Command::Pointer. Since Command inherits from LightObject, at this
* point in the code, only a pointer or a reference to the Command can
* be used. */
Command* GetCommand(unsigned long tag);
/** Call Execute on all the Commands observing this event id. */
void InvokeEvent( const Event & );
/** Call Execute on all the Commands observing this event id.
* The actions triggered by this call doesn't modify this object. */
void InvokeEvent( const Event & ) const;
/** Remove the observer with this tag value. */
void RemoveObserver(unsigned long tag);
/** Remove all observers . */
void RemoveAllObservers();
/** Return true if an observer is registered for this event. */
bool HasObserver( const Event & event ) const;
protected:
private:
SubjectInternals *Internals;
private:
};
} // end namespace gdcm
#endif //GDCMSUBJECT_H
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