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Teuchos_Describable.hpp
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00041 
00042 #ifndef TEUCHOS_DESCRIBABLE_HPP
00043 #define TEUCHOS_DESCRIBABLE_HPP
00044 
00045 #include "Teuchos_VerbosityLevel.hpp"
00046 #include "Teuchos_FancyOStream.hpp"
00047 #include "Teuchos_LabeledObject.hpp"
00048 
00049 
00050 namespace Teuchos {
00051 
00052 
00076 class TEUCHOSCORE_LIB_DLL_EXPORT Describable : virtual public LabeledObject {
00077 public:
00079   static const EVerbosityLevel verbLevel_default;
00080 
00082 
00083 
00095   virtual std::string description() const;
00096 
00148   virtual void
00149   describe (FancyOStream &out,
00150             const EVerbosityLevel verbLevel = verbLevel_default) const;
00151 
00162   void
00163   describe (std::ostream &out,
00164             const EVerbosityLevel verbLevel = verbLevel_default) const;
00165 
00167   virtual ~Describable ();
00168 };
00169 
00170 
00171 // Describable stream manipulator state class
00172 //
00173 // This is not a class that a user needs to see and that is why it is not
00174 // being given doxygen documentation!
00175 struct DescribableStreamManipulatorState {
00176   const Describable &describable;
00177   const EVerbosityLevel verbLevel;
00178   DescribableStreamManipulatorState(
00179     const Describable &_describable,
00180     const EVerbosityLevel _verbLevel = VERB_MEDIUM
00181     )
00182     :describable(_describable)
00183     ,verbLevel(_verbLevel)
00184     {}
00185 };
00186 
00187 
00209 inline DescribableStreamManipulatorState describe(
00210   const Describable &describable,
00211   const EVerbosityLevel verbLevel = Describable::verbLevel_default
00212   )
00213 {
00214   return DescribableStreamManipulatorState(describable,verbLevel);
00215 }
00216 
00217 
00244 inline
00245 std::ostream& operator<<(
00246   std::ostream& os, const DescribableStreamManipulatorState& d
00247   )
00248 {
00249   d.describable.describe(*getFancyOStream(Teuchos::rcp(&os,false)),d.verbLevel);
00250   return os;
00251 }
00252 
00253 //
00254 // RAB: Note: The above function works with an std::ostream object even
00255 // through Describable::describe(...) requires a FancyOStream object.  We must
00256 // write the stream manipulator in terms of std::ostream, or compound output
00257 // statements like:
00258 //
00259 //  void foo( FancyOStream &out, Describable &d, EVerbLevel verbLevel )
00260 //    {
00261 //      out << "\nThis is the describable object d:" << describe(d,verbLevel);
00262 //    }
00263 //
00264 // will not work correctly.  The problem is that the first output
00265 //
00266 //   out << "\nThis is the describable object d:"
00267 //
00268 //  must return a reference to an std::ostream object.  This should mean that
00269 //  the next statement, which is basically:
00270 //
00271 //    static_cast<std::ostream&>(out) << DescribableStreamManipulatorState
00272 //
00273 // should not even compile.  However, under gcc 3.4.3, the code did compile
00274 // but did not call the above function.  Instead, it set up some type of
00275 // infinite recursion that resulted in a segfault due to the presence of the
00276 // Teuchos::any class!
00277 //
00278 
00279 
00280 } // namespace Teuchos
00281 
00282 #endif // TEUCHOS_DESCRIBABLE_HPP
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