ostream-like interface to creating log messages. More...

#include <LogIO.h>

Inheritance diagram for casa::LogIO:

Public Types
enum	Command { POST, EXCEPTION, SEVERE, WARN, NORMAL, NORMAL1, NORMAL2, NORMAL3, NORMAL4, NORMAL5, DEBUG1, DEBUG2, DEBUGGING }
	Special commands to the LogIO object. More...
Public Member Functions
	LogIO ()
	Attach this LogIO object to the global sink with no origin information.
	LogIO (LogSink &sink)
	Attach this LogIO object to the supplied sink.
	LogIO (const LogOrigin &OR)
	Attach this LogIO object to the supplied origin and global sink.
	LogIO (const LogOrigin &OR, LogSink &sink)
	Attach this LogIO object to the supplied origin and sink.
	LogIO (const LogIO &other)
	Copying uses reference semantics, i.e.
LogIO &	operator= (const LogIO &other)
	~LogIO ()
	The destructor will post any accumulated message that has not already been posted.
void	post ()
	Post the accumulated message.
void	post (LogMessage &amess)
void	postLocally ()
	Post the accumulated message locally.
template<typename EXC >
void	postThenThrow (const EXC &exc)
	Post the accumulated message at SEVERE priority and then throw an exception.
void	priority (LogMessage::Priority which)
	Change the priority of the message.
LogMessage::Priority	priority ()
void	sourceLocation (const SourceLocation *where)
	Change the location in the origin.
void	origin (const LogOrigin &origin)
	Change the origin of the accumulated message.
ostream &	output ()
	Acumulate output in this ostream.
LogSinkInterface &	localSink ()
	Occasionally it is useful to interrogate the local log sink.
const LogSinkInterface &	localSink () const
Private Member Functions
void	preparePostThenThrow (const AipsError &x)
	Prepare message stream for postThenThrow function.
Private Attributes
LogSink	sink_p
LogMessage	msg_p
ostringstream *	text_p

Detailed Description

ostream-like interface to creating log messages.

Intended use:

Public interface

Review Status

Reviewed By:: UNKNOWN
Date Reviewed:: before2004/08/25
Test programs:: tLogIO
Demo programs:: dLogging

Prerequisite

LogSink class
LogMessage class
LogOrigin class

Etymology

Log message, Input/Output.

Synopsis

LogIO is intended to be used in a way similar to the ostream class. However, rather than sending it's output to a file or stdout, it bundles its output up into LogMessage objects and posts them to a LogSink .

When you use the "<<" operator on a LogIO, you are building up a log message inside the LogIO object. The message is posted when:

LogIO::post() is called
You send the LogIO::POST or LogIO::EXCEPTION commands to the LogIO with the shift ( << ) command.
The LogIO object is destructed.

Note that log messages may span multiple lines, so sending the LogIO a newline (via "\n" or endl) does not force the message to be emitted.

Example

A LogIO may be created in the following ways:

       LogIO   os;

Here, os is attached to the global log sink, and no origin information is set.

       TableLogSink tab(...);
       LogIO   os(tab);

Here, os is attached to tab (and also to the global log sink since every sink's post also calls the global sink's post).

       LogIO   os(LogOrigin("class", "func(args)", WHERE));

Here, os is attached to the global sink and the origin information is set to class::func(args) and the line number and source file information is set (with WHERE).

       TableLogSink tab(...);
       LogIO   os(LogOrigin("class", "func(args)", WHERE), tab);

Here all the above information is set.

Once you have a LogIO, using it is pretty simple:

      os << "Every good boy deserves" << 5 << " pieces of fudge!";

This accumulates the message but does not send it. If you want to force it to be sent you can do so with either of the following methods:

       os << LogIO::POST;     // From the Commands enum
       os.post();             // Member function

Note that after a post the priority is reset to NORMAL.

If you want to change the level of the message you can also do so with the shift operator:

      os << LogIO::DEBUGGING << "Boring message" << 
            LogIO::SEVERE << "Error!" << LogIO::POST;

Note that changing the priority changes the priority of the entire message. The message does not get posted until the POST is done. So in the above example the DEBUGGING priority does not do anything because the priority is overwritten by the SEVERE one.

You can also change the origin information with the << operator:

       os << LogOrigin("class", "func(args)");
       os << WHERE;

A class which has an operator<< to std::ostream but not LogIO can be handled like so:

    os << LogIO::SEVERE << " at ";
    os.output() << MEpoch::Convert(time_p, MEpoch::Ref(MEpoch::UTC))();
    os << LogIO::POST;

Motivation

The earlier method of creating log messages solely through LogSink and LogMessage required the programmer to type in more lines of code than this solution. Also, this interface makes it easy to drop log messages into existing code that uses ostreams.

To Do

Add << operators for all classes that have ostream<< defined. (We could probably do it with a template, but might result in ambiguity).
Have a function for changing the LogSink only? (You can get much the same effect with operator=). them?

Definition at line 166 of file LogIO.h.

Member Enumeration Documentation

enum casa::LogIO::Command

Special commands to the LogIO object.

Enumerator:

POST	Post the accumulated message. Equivalent to calling LogIO::post().
EXCEPTION	Post the accumulated message then throw an exception. Always posts the message at SEVERE priority. Equivalent to calling LogIO::postThenThrow().
SEVERE	Change the message priority to SEVERE.
WARN	Change the message priority to WARN.
NORMAL	Change the message priority to NORMAL.
NORMAL1
NORMAL2
NORMAL3
NORMAL4
NORMAL5
DEBUG1	Change the message priority to DEBUGGING.
DEBUG2
DEBUGGING

Definition at line 170 of file LogIO.h.

Constructor & Destructor Documentation

casa::LogIO::LogIO ( )

Attach this LogIO object to the global sink with no origin information.

casa::LogIO::LogIO ( LogSink & sink )

Attach this LogIO object to the supplied sink.

A referencing copy of the sink is made inside the LogIO object, so you do not need to worry about memory management.

casa::LogIO::LogIO ( const LogOrigin & OR )

Attach this LogIO object to the supplied origin and global sink.

casa::LogIO::LogIO	(	const LogOrigin &	OR,
		LogSink &	sink
	)

Attach this LogIO object to the supplied origin and sink.

casa::LogIO::LogIO ( const LogIO & other )

Copying uses reference semantics, i.e.

the same sink will be shared by both copies.

casa::LogIO::~LogIO ( )

The destructor will post any accumulated message that has not already been posted.

Member Function Documentation

LogSinkInterface & casa::LogIO::localSink ( ) [inline]

Occasionally it is useful to interrogate the local log sink.

Definition at line 300 of file LogIO.h.

References casa::LogSink::localSink(), and sink_p.

const LogSinkInterface & casa::LogIO::localSink ( ) const [inline]

Definition at line 305 of file LogIO.h.

References casa::LogSink::localSink(), and sink_p.

LogIO& casa::LogIO::operator= ( const LogIO & other )

void casa::LogIO::origin ( const LogOrigin & origin )

Change the origin of the accumulated message.

ostream& casa::LogIO::output ( )

Acumulate output in this ostream.

void casa::LogIO::post ( )

Post the accumulated message.

If you wish, you can post the messages only locally to the sink. After the post the priority is reset to NORMAL.

Reimplemented in casa::GLLogIO.

void casa::LogIO::post ( LogMessage & amess )

void casa::LogIO::postLocally ( )

Post the accumulated message locally.

After the post the priority is reset to NORMAL.

template<typename EXC >

void casa::LogIO::postThenThrow ( const EXC & exc ) [inline]

Post the accumulated message at SEVERE priority and then throw an exception.

After the post the priority is reset to NORMAL.

Definition at line 228 of file LogIO.h.

References msg_p, casa::LogSink::postThenThrow(), preparePostThenThrow(), and sink_p.

void casa::LogIO::preparePostThenThrow ( const AipsError & x ) [private]

Prepare message stream for postThenThrow function.

Referenced by postThenThrow().

void casa::LogIO::priority ( LogMessage::Priority which )

Change the priority of the message.

It does NOT post the accumulated message at the old priority first.

LogMessage::Priority casa::LogIO::priority ( )

void casa::LogIO::sourceLocation ( const SourceLocation * where )

Change the location in the origin.

Almost always this is called with the macro WHERE as its argument.

Member Data Documentation

LogMessage casa::LogIO::msg_p [private]

Definition at line 253 of file LogIO.h.

Referenced by postThenThrow().

LogSink casa::LogIO::sink_p [private]

Definition at line 252 of file LogIO.h.

Referenced by localSink(), and postThenThrow().

ostringstream* casa::LogIO::text_p [private]

Definition at line 254 of file LogIO.h.

The documentation for this class was generated from the following file:

casacore/casa/Logging/LogIO.h

Public Types

Public Member Functions

Private Member Functions

Private Attributes