Teuchos_Describable.hpp

// @HEADER
// ***********************************************************************
// 
//                    Teuchos: Common Tools Package
//                 Copyright (2004) Sandia Corporation
// 
// Under terms of Contract DE-AC04-94AL85000, there is a non-exclusive
// license for use of this work by or on behalf of the U.S. Government.
// 
// This library is free software; you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; either version 2.1 of the
// License, or (at your option) any later version.
//  
// This library is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//  
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
// USA
// Questions? Contact Michael A. Heroux (maherou@sandia.gov) 
// 
// ***********************************************************************
// @HEADER

#ifndef TEUCHOS_DESCRIBABLE_HPP
#define TEUCHOS_DESCRIBABLE_HPP

#include "Teuchos_VerbosityLevel.hpp"
#include "Teuchos_FancyOStream.hpp"

namespace Teuchos {

class Describable {
public:

  static const EVerbosityLevel   verbLevel_default;

  virtual ~Describable() {}



  virtual std::string description() const;

  virtual void describe(
    FancyOStream                &out
    ,const EVerbosityLevel      verbLevel     = verbLevel_default
    ) const;
  
};

// Describable stream manipulator state class
//
// This is not a class that a user needs to see and that is why it is not
// being given doxygen documentation!
struct DescribableStreamManipulatorState {
  const Describable          &describable;
  const EVerbosityLevel      verbLevel;
  DescribableStreamManipulatorState(
    const Describable          &_describable
    ,const EVerbosityLevel     _verbLevel=VERB_MEDIUM
    )
    :describable(_describable)
    ,verbLevel(_verbLevel)
    {}
};

inline DescribableStreamManipulatorState describe(
  const Describable          &describable
  ,const EVerbosityLevel     verbLevel     = Describable::verbLevel_default
  )
{
  return DescribableStreamManipulatorState(describable,verbLevel);
}

inline
std::ostream& operator<<( std::ostream& os, const DescribableStreamManipulatorState& d )
{
  d.describable.describe(*getFancyOStream(Teuchos::rcp(&os,false)),d.verbLevel);
  return os;
}

//
// RAB: Note: The above function works with an std::ostream object even
// through Describable::describe(...) requires a FancyOStream object.  We must
// write the stream manipulator in terms of std::ostream, or compound right
// statements like:
//
//  void foo( FancyOStream &out, Describable &d, EVerbLevel verbLevel )
//    {
//      out << "\nThis is the describable object d:" << describe(d,verbLevel);
//    }
//
// will not work currectly.  The problem is that the first output
//
//   out << "\nThis is the describable object d:"
//
//  must return a reference to an std::ostream object.  This should mean that
//  the next statement, which is basically:
//
//    static_cast<std::ostream&>(out) << DescribableStreamManipulatorState
//
// should not even compile.  However, under gcc 3.4.3, the code did compile
// but did not call the above function.  Instead, it set up some type of
// infinite recursion that resulted in a segfault.
//

} // namespace Teuchos

#endif // TEUCHOS_DESCRIBABLE_HPP

---