source: src/CodePatterns/Creator.hpp@ c1e104

/*
 * Creator.hpp
 *
 *  Created on: Jan 3, 2011
 *      Author: heber
 */

#ifndef CREATOR_HPP_
#define CREATOR_HPP_

// include config.h
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

/** \section <Creator> (Creator Howto)
 *
 * This pattern is sometimes called 'type erasure': we want to present
 * the user with a abstract interface only (name) but in
 * order to create a copy (such that handed out instances are independent from
 * one another) we have to know about the type of underlying (complex) class.
 *
 * Hence, we create this templated creator class (Creator<name,T>), which has an
 * abstract creation interface (ICreator<name>). name distinguishes distinct
 * ICreator interface classes, the second template argument T is the wrapped
 * class to create by Creator.
 *
 * This pattern is e.g. very useful when multiple (proto)types have to be
 * stored in the table of a factory. Factories can serve only a general
 * (abstract) type and not the specific one due to a necessary general function
 * signature.
 *
 * <h1> Howto </h1>
 *
 * simply include "Creator.hpp" in your file and inherit it, e.g.
 * @code
 * template <class T>
 * class MyParticularType :
 *   public CommonInterface,
 *   public Creator<
 *     CommonInterface,
 *     MyParticularType<T> >
 * {};
 * @encode
 * i.e. here MyParticularType will wrap all desired types T, where
 * CommonInterface is an abstract base class that defines all stuff common
 * for all possible types T.
 *
 */
template <class name>
struct ICreator
{
  virtual ~ICreator() {}
  virtual name * create() const =0;
};

template <class name, class T>
struct Creator : public ICreator<name>
{
  virtual name * create() const {
    return new T();
  }
};


#endif /* CREATOR_HPP_ */