Teuchos - Trilinos Tools Package Version of the Day
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 
00081 class TEUCHOS_LIB_DLL_EXPORT Describable : virtual public LabeledObject {
00082 public:
00083 
00085   static const EVerbosityLevel   verbLevel_default;
00086 
00088 
00089 
00100   virtual std::string description() const;
00101 
00137   virtual void describe(
00138     FancyOStream &out,
00139     const EVerbosityLevel verbLevel = verbLevel_default
00140     ) const;
00141   
00142 };
00143 
00144 
00145 // Describable stream manipulator state class
00146 //
00147 // This is not a class that a user needs to see and that is why it is not
00148 // being given doxygen documentation!
00149 struct DescribableStreamManipulatorState {
00150   const Describable &describable;
00151   const EVerbosityLevel verbLevel;
00152   DescribableStreamManipulatorState(
00153     const Describable &_describable,
00154     const EVerbosityLevel _verbLevel = VERB_MEDIUM
00155     )
00156     :describable(_describable)
00157     ,verbLevel(_verbLevel)
00158     {}
00159 };
00160 
00161 
00183 inline DescribableStreamManipulatorState describe(
00184   const Describable &describable,
00185   const EVerbosityLevel verbLevel = Describable::verbLevel_default
00186   )
00187 {
00188   return DescribableStreamManipulatorState(describable,verbLevel);
00189 }
00190 
00191 
00218 inline
00219 std::ostream& operator<<(
00220   std::ostream& os, const DescribableStreamManipulatorState& d
00221   )
00222 {
00223   d.describable.describe(*getFancyOStream(Teuchos::rcp(&os,false)),d.verbLevel);
00224   return os;
00225 }
00226 
00227 //
00228 // RAB: Note: The above function works with an std::ostream object even
00229 // through Describable::describe(...) requires a FancyOStream object.  We must
00230 // write the stream manipulator in terms of std::ostream, or compound output
00231 // statements like:
00232 //
00233 //  void foo( FancyOStream &out, Describable &d, EVerbLevel verbLevel )
00234 //    {
00235 //      out << "\nThis is the describable object d:" << describe(d,verbLevel);
00236 //    }
00237 //
00238 // will not work correctly.  The problem is that the first output
00239 //
00240 //   out << "\nThis is the describable object d:"
00241 //
00242 //  must return a reference to an std::ostream object.  This should mean that
00243 //  the next statement, which is basically:
00244 //
00245 //    static_cast<std::ostream&>(out) << DescribableStreamManipulatorState
00246 //
00247 // should not even compile.  However, under gcc 3.4.3, the code did compile
00248 // but did not call the above function.  Instead, it set up some type of
00249 // infinite recursion that resulted in a segfault due to the presence of the
00250 // Teuchos::any class!
00251 //
00252 
00253 
00254 } // namespace Teuchos
00255 
00256 #endif // TEUCHOS_DESCRIBABLE_HPP
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