eo/src/eoID.h

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+// -*- mode: c++; c-indent-level: 4; c++-member-init-indent: 8; comment-column: 35; -*-
+
+//-----------------------------------------------------------------------------
+// eoID.h
+// (c) GeNeura Team, 1998
+//-----------------------------------------------------------------------------
+
+#ifndef EOID_H
+#define EOID_H
+
+//-----------------------------------------------------------------------------
+
+#include <iostream>  // istream, ostream
+#include <string> // for string
+
+using namespace std;
+
+//-----------------------------------------------------------------------------
+// eoID
+//-----------------------------------------------------------------------------
+
+/** eoID is a template class that adds an ID to an object.\\
+Requisites for template instantiation are that the object must admit a default ctor 
+and a copy ctor. The Object must be an eoObject, thus, it must have its methods: className,
+printOn, readFrom, that is why we don´t subclass eoObject to avoid multiple inheritance.\\
+IDs can be used to count objects of a a kind, or track them, or whatever.
+@see eoObject
+*/
+template <class Object>
+class eoID: public Object
+{
+ public:
+	/// Main ctor from an already built Object.
+	eoID( const Object& _o): Object( _o ), thisID(globalID++) {};
+
+	/// Copy constructor.
+	eoID( const eoID& _id): Object( _id ), thisID(globalID++ ) {};
+
+  /// Virtual dtor. They are needed in virtual class hierarchies
+  virtual ~eoID() {};
+  
+
+  ///returns the age of the object
+  unsigned long ID() const {return thisID;}
+
+  	/** @name Methods from eoObject
+	readFrom and printOn are directly inherited from eo1d
+	*/
+	//@{
+  /** Return the class id. This should be redefined in each class; but 
+  it's got code as an example of implementation. Only "leaf" classes
+  can be non-virtual.
+  */
+  virtual string className() const { return string("[eoID]")+Object::className(); };
+
+  /**
+   * Read object.
+   * @param _is A istream.
+   * @throw runtime_exception If a valid object can't be read.
+   */
+  virtual void readFrom(istream& _is) {
+	  Object::readFrom( _is );
+	  _is >> thisID;
+  }
+
+  
+  /**
+   * Write object. It's called printOn since it prints the object _on_ a stream.
+   * @param _os A ostream.
+   */
+  virtual void printOn(ostream& _os) const{
+	  Object::printOn( _os );
+	  _os << thisID;
+  }
+//@}
+  
+ private:
+
+	 /** Default Constructor. \\
+	 It´s private so that it is not used anywhere; the right way of using this object
+	 is to create an Object and passing it to an aged by means of the copy ctor; that way
+	 it´s turned into an Aged object*/
+	 eoID(): Object(), thisID( globalID++ ) {};
+
+	 unsigned long thisID;
+	 static unsigned long globalID;
+};
+
+template< class Object>
+unsigned long eoID< Object >::globalID = 0;
+
+#endif EOID_H