ECGetterBase.h

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#ifndef Utilities_ECGetterBase_h
#define Utilities_ECGetterBase_h
// -*- C++ -*-
//
// Package:     Utilities
// Class  :     ECGetterBase
//
//
// Original Author:  Chris Jones
//         Created:  Fri Sep 22 12:41:05 EDT 2006
//
 
// system include files
 
// user include files
 
// forward declarations
namespace edm {
  namespace extensioncord {
    template <class T>
    class ECGetterBase {
    public:
      ECGetterBase() : data_(nullptr) {}
      virtual ~ECGetterBase() {}
 
      // ---------- const member functions ---------------------
      const T* get() const {
        if (data_ == nullptr) {
          data_ = this->getImpl();
        }
        return data_;
      }
 
    private:
      //ECGetterBase(const ECGetterBase&); // allow default
 
      //const ECGetterBase& operator=(const ECGetterBase&); // allow default
 
      //the actual method which is used to get the requested data
      virtual const T* getImpl() const = 0;
 
      // ---------- member data --------------------------------
      //does not own the data
      mutable const T* data_;
    };
  }  // namespace extensioncord
  template <class T>
  class ValueHolderECGetter : public extensioncord::ECGetterBase<T> {
  public:
    ValueHolderECGetter(const T& iValue) : value_(&iValue) {}
 
  private:
    const T* getImpl() const override { return value_; }
    const T* value_;
  };
}  // namespace edm
 
#endif