Debug output

Modules
	Standard Debug Streams

Files
file	debugstream.hh
	Defines several output streams for messages of different importance.

Classes
struct	Dune::greater_or_equal< current, threshold >
	Greater or equal template test. More...
struct	Dune::common_bits< current, mask >
	activate if current and mask have common bits switched on. More...
class	Dune::DebugStreamError
	standard exception for the debugstream More...
class	Dune::DebugStreamState
	Intermediate class to implement tie-operation of DebugStream. More...
class	Dune::DebugStream< thislevel, dlevel, alevel, activator >
	Generic class to implement debug output streams. More...

Typedefs
typedef unsigned int	Dune::DebugLevel
	Type for debug levels. More...

Functions
	Dune::DebugStream< thislevel, dlevel, alevel, activator >::DebugStream (std::ostream &out=std::cerr)
	Create a DebugStream and set initial output stream. More...
	Dune::DebugStream< thislevel, dlevel, alevel, activator >::DebugStream (DebugStreamState &master, std::ostream &fallback=std::cerr)
	Create a DebugStream and directly tie to another DebugStream. More...
	Dune::DebugStream< thislevel, dlevel, alevel, activator >::~DebugStream () noexcept(false)
	Destroy stream. More...
template<class T >
DebugStream &	Dune::DebugStream< thislevel, dlevel, alevel, activator >::operator<< (const T data)
	Generic types are passed on to current output stream.
DebugStream &	Dune::DebugStream< thislevel, dlevel, alevel, activator >::operator<< (const int data)
	explicit specialization so that enums can be printed More...
DebugStream &	Dune::DebugStream< thislevel, dlevel, alevel, activator >::operator<< (std::ostream &(*f)(std::ostream &))
	pass on manipulators to underlying output stream
DebugStream &	Dune::DebugStream< thislevel, dlevel, alevel, activator >::flush ()
	pass on flush to underlying output stream
void	Dune::DebugStream< thislevel, dlevel, alevel, activator >::push (bool b)
	set activation flag and store old value
void	Dune::DebugStream< thislevel, dlevel, alevel, activator >::pop () throw (DebugStreamError)
	restore previously set activation flag
bool	Dune::DebugStream< thislevel, dlevel, alevel, activator >::active () const
	reports if this stream will produce output More...
void	Dune::DebugStream< thislevel, dlevel, alevel, activator >::attach (std::ostream &stream)
	set output to a different stream. More...
void	Dune::DebugStream< thislevel, dlevel, alevel, activator >::detach () throw (DebugStreamError)
	detach current output stream and restore to previous stream
void	Dune::DebugStream< thislevel, dlevel, alevel, activator >::untie () throw (DebugStreamError)
	Untie stream.

Variables
StreamWrap *	Dune::DebugStreamState::current
	current output stream and link to possibly pushed old output streams
bool	Dune::DebugStreamState::_active
	flag to switch output during runtime
bool	Dune::DebugStreamState::_tied
	are we tied to another DebugStream?
unsigned int	Dune::DebugStreamState::_tied_streams
	how many streams are tied to this state

Detailed Description

The debug output is implemented by instances of DebugStream which provides the following features:

• output-syntax in the standard ostream-notation
• output can be totally deactivated depending on template parameters
• streams with active output can be deactivated during runtime
• redirecting to std::ostream or other DebugStream s during runtime
• stack oriented state

The Dune-components should use the streams explained in Standard Debug Streams for output so that applications may redirect the output globally.

Changes in runtime are provided by three sets of methods:

• push()/pop() sets new activation flag or restore old setting
• attach()/detach() redirects output to a different std::ostream or restore old stream
• tie()/untie() redirects output through another DebugStream. If the state of the master stream changes (activation or output-stream) it is changed in the tied stream as well

The first methods implement a full stack whereas tie() is a bit different: though a tied stream may be (de)activated via push()/pop() you cannot attach() or detach() an output. You'll need to change the master stream instead.

Applications

Applications using the Dune-library should create an independent set of DebugStreams so that the debug levels can be changed separately. Example:

static const Dune::DebugLevel APPL_MINLEVEL = 3;
 
Dune::DebugStream<1, APPL_MINLEVEL> myverbose;
Dune::DebugStream<2, APPL_MINLEVEL> myinfo;
Dune::DebugStream<3, APPL_MINLEVEL> mywarn;

This code creates three streams of which only the last one really creates output. The output-routines of the other streams vanish in optimized executables.

You can use the common_bits-Template to switch to a policy using bitflags:

enum { APPL_CORE = 1, APPL_IO = 2, APPL_GRAPHICS = 4};
 
static const Dune::DebugLevel APPL_DEBUG_MASK = APPL_CORE | APPL_GRAPHICS;
static const Dune::DebugLevel APPL_ACTIVE_MASK = 0xff;
 
Dune::DebugStream<APPL_CORE, APPL_DEBUG_MASK, APPL_ACTIVE_MASK, Dune::common_bits> coreout;
Dune::DebugStream<APPL_IO, APPL_DEBUG_MASK, APPL_ACTIVE_MASK, Dune::common_bits> ioout;
Dune::DebugStream<APPL_GRAPHICS, APPL_DEBUG_MASK, APPL_ACTIVE_MASK, Dune::common_bits> graphout;

Applications that wish to redirect the Standard Debug Streams through their private streams may use the tie()-mechanism:

// initialize streams like above
 
Dune::dwarn.tie(coreout);
 
// ... Dune-output to dwarn will be directed through coreout ...
 
Dune::dwarn.untie();

Keep in mind to untie() a stream before the tied stream is destructed.

An alternative is to attach() an output stream defined by the application:

std::ofstream mylog("application.log");
 
Dune::dwarn.attach(mylog);

standard debug streams with level below MINIMAL_DEBUG_LEVEL will collapse to doing nothing if output is requested.

MINIMAL_DEBUG_LEVEL is set to DUNE_MINIMAL_DEBUG_LEVEL, which is defined in config.h and can be changed by the configure option

--with-minimal-debug-level=[grave|warn|info|verb|vverb] 

For a Dune-Release this should be set to at least 4 so that only important messages are active. Dune-developers may adapt this setting to their debugging needs locally

Keep in mind that libdune has to be recompiled if this value is changed!

The singleton instances of the available debug streams can be found in the Standard Debug Streams module

Typedef Documentation

DebugLevel

typedef unsigned int Dune::DebugLevel

Type for debug levels.

Only positive values allowed

Function Documentation

active()

template<DebugLevel thislevel = 1, DebugLevel dlevel = 1, DebugLevel alevel = 1, template< DebugLevel, DebugLevel > class activator = greater_or_equal>

bool Dune::DebugStream< thislevel, dlevel, alevel, activator >::active ( ) const

inline

reports if this stream will produce output

a DebugStream that is deactivated because of its level will always return false, otherwise the state of the internal activation is returned

References Dune::DebugStreamState::_active.

attach()

template<DebugLevel thislevel = 1, DebugLevel dlevel = 1, DebugLevel alevel = 1, template< DebugLevel, DebugLevel > class activator = greater_or_equal>

void Dune::DebugStream< thislevel, dlevel, alevel, activator >::attach ( std::ostream &  stream )

inline

set output to a different stream.

Old stream data is stored

References Dune::DebugStreamState::_tied, Dune::DebugStreamState::current, and DUNE_THROW.

DebugStream() [1/2]

template<DebugLevel thislevel = 1, DebugLevel dlevel = 1, DebugLevel alevel = 1, template< DebugLevel, DebugLevel > class activator = greater_or_equal>

Dune::DebugStream< thislevel, dlevel, alevel, activator >::DebugStream ( DebugStreamState &  master, std::ostream &  fallback = std::cerr  )

inline

Create a DebugStream and directly tie to another DebugStream.

The fallback is used if a DebugStream constructed via this method is untie()ed later. Otherwise the stream would be broken afterwards.

References Dune::DebugStreamState::_active, Dune::DebugStreamState::_tied, Dune::DebugStreamState::_tied_streams, and Dune::DebugStreamState::current.

DebugStream() [2/2]

template<DebugLevel thislevel = 1, DebugLevel dlevel = 1, DebugLevel alevel = 1, template< DebugLevel, DebugLevel > class activator = greater_or_equal>

Dune::DebugStream< thislevel, dlevel, alevel, activator >::DebugStream ( std::ostream &  out = std::cerr )

inline

Create a DebugStream and set initial output stream.

during runtime another stream can be attach()ed, however the initial stream may not be detach()ed.

References Dune::DebugStreamState::_active, Dune::DebugStreamState::_tied, Dune::DebugStreamState::_tied_streams, and Dune::DebugStreamState::current.

operator<<()

template<DebugLevel thislevel = 1, DebugLevel dlevel = 1, DebugLevel alevel = 1, template< DebugLevel, DebugLevel > class activator = greater_or_equal>

DebugStream & Dune::DebugStream< thislevel, dlevel, alevel, activator >::operator<< ( const int  data )

inline

explicit specialization so that enums can be printed

Operators for built-in types follow special rules (§11.2.3) so that enums won't fit into the generic method above. With an existing operator<< for int however the enum will be automatically casted.

References Dune::DebugStreamState::_active, Dune::DebugStreamState::_tied, and Dune::DebugStreamState::current.

~DebugStream()

template<DebugLevel thislevel = 1, DebugLevel dlevel = 1, DebugLevel alevel = 1, template< DebugLevel, DebugLevel > class activator = greater_or_equal>

Dune::DebugStream< thislevel, dlevel, alevel, activator >::~DebugStream ( )

inlinenoexcept

Destroy stream.

if other streams still tie() to this stream an exception will be thrown. Otherwise the child streams would certainly break on the next output

References Dune::DebugStreamState::_tied, Dune::DebugStreamState::_tied_streams, Dune::DebugStreamState::current, and DUNE_THROW.