Resource.h

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//-*-c++-*-
#ifndef INCLUDED_Resource_h_
#define INCLUDED_Resource_h_

//! Provides a generic interface for resources which need to keep track of when they are in use, such as mutex locks
class Resource {
public:
  //! base class for holding data required for requesting to use/release the resource
  class Data {
  public:
    virtual ~Data() {} //!< empty virtual destructor to mark this as a base class
  };
  static Data emptyData; //!< to use as the data reference when none is needed/specified
  
  //! destructor (does nothing -- up to subclass if they need to release resource)
  virtual ~Resource() {}
  
  virtual void useResource(Data& d)=0; //!< marks the resource as in use
  virtual void releaseResource(Data& d)=0; //!< releases the resource
};

//! a no-op resource, since we don't want Resource itself to be directly instantiatable
class EmptyResource : public Resource {
public: 
  virtual void useResource(Data&) {} //!< would mark the resource in use, here is a no-op
  virtual void releaseResource(Data&) {} //!< would mark the resource no longer in use, here is a no-op
};
extern EmptyResource emptyResource; //!< a global instance of the empty resource, for no-op situations

/*! @file
 * @brief Describes Resource (and EmptyResource), which provides a generic interface for resources which need to keep track of when they are in use, such as mutex locks
 * @author Ethan Tira-Thompson (ejt) (Creator)
 */

#endif