ExtensionCord.h

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#ifndef Utilities_ExtensionCord_h
#define Utilities_ExtensionCord_h
// -*- C++ -*-
//
// Package:     Utilities
// Class  :     ExtensionCord
//
//
// Original Author:  Chris Jones
//         Created:  Fri Sep 22 12:38:58 EDT 2006
//

// system include files
#include <memory>

// user include files
#include "FWCore/Utilities/interface/ECGetterBase.h"
#include "FWCore/Utilities/interface/Exception.h"

// forward declarations

namespace edm {
  template <class T>
  class OutletBase;

  template <class T>
  class ExtensionCord {
    //only something that inherits from OutletBase<T> will
    // be allowed to call 'setGetter'
    friend class OutletBase<T>;

  public:
    struct Holder {
      extensioncord::ECGetterBase<T>* getter_;
    };

    ExtensionCord() : holder_(new Holder()) {}
    //virtual ~ExtensionCord();

    // ---------- const member functions ---------------------
    const T* operator->() const { return this->get(); }

    const T* get() const {
      if (!this->connected()) {
        throw cms::Exception("InvalidExtensionCord") << "an edm::ExtensionCord for type " << typeid(T).name()
                                                     << " was not connected to an outlet. This is a programming error.";
      }
      return holder_->getter_->get();
    }

    const T& operator*() const { return *(this->get()); }

    bool connected() const { return 0 != holder_->getter_; }
    // ---------- static member functions --------------------

    // ---------- member functions ---------------------------

  private:
    //ExtensionCord(const ExtensionCord&); // allow default

    //const ExtensionCord& operator=(const ExtensionCord&); // allow default

    void setGetter(extensioncord::ECGetterBase<T>* iGetter) { holder_->getter_ = iGetter; }
    // ---------- member data --------------------------------
    std::shared_ptr<Holder> holder_;
  };
}  // namespace edm

#endif