Added an utility class to update a value from a getter method

eo/src/utils/eoGetterUpdater.h

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+/*
+
+(c) Thales group, 2010
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Lesser General Public
+    License as published by the Free Software Foundation;
+    version 2 of the License.
+
+    This library 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
+    Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public
+    License along with this library; if not, write to the Free Software
+    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+Contact: http://eodev.sourceforge.net
+
+Authors:
+Lionel Parreaux <lionel.parreaux@gmail.com>
+
+*/
+
+#ifndef _eoGetterUpdater_h
+#define _eoGetterUpdater_h
+
+#include <utils/eoUpdater.h>
+
+template <class EOT> class eoCheckPoint;
+
+/**
+    eoGetterUpdater is an eoUpdater that updates its eoValueParam::value() from
+    the specified object and the specified getter method on this object.
+    
+    @ingroup Utilities
+*/
+template <class T, class V = double>
+class eoGetterUpdater : public eoUpdater, public eoValueParam<V>
+{
+public:
+    using eoValueParam<V>::value;
+    
+    virtual std::string className(void) const { return "eoGetterUpdater"; }
+    
+    typedef V (T::*MethodType)();
+    
+    eoGetterUpdater(T& _instance, MethodType _method)
+    : instance(_instance), method(_method)
+    { }
+    
+    // Overload to accept const getter methods; safely casts them to non-const
+    eoGetterUpdater(T& _instance, V (T::*_method)() const)
+    : instance(_instance), method((MethodType)_method)
+    { }
+    
+    virtual void operator()()
+    {
+        value() = (instance.*method)();
+    }
+    
+private:
+    T& instance;
+    MethodType method; // ie:  V (T::*method)();
+};
+
+
+
+#endif
+
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