FBB::Log(3bobcat)
Log messages
(libbobcat-dev_4.08.03-x.tar.gz)
2005-2018
NAME
FBB::Log - std::ostream handling log messages
SYNOPSIS
#include <bobcat/log>
Linking option: -lbobcat
DESCRIPTION
The class FBB::Log is an std::ostream initialized with a
FBB::LogBuffer. It is used to send log-messages to the (r)syslog
stream. Refer to the logbuffer(3bobcat) man-page for details about this
process.
NAMESPACE
FBB
All constructors, members, operators and manipulators, mentioned in this
man-page, are defined in the namespace FBB.
INHERITS FROM
std::ostream
ENUMERATIONS
The enumeration TimeStamps is defined in the namespace FBB,
primarily for initializing FBB::LogBuffer objects. It is used with
FBB::Log members as well. It has the following values:
- NOTIMESTAMPS:
Log-messages will not have timestamps prepended to them.
- TIMESTAMPS:
Log-messages will have timestamps prepended to them.
- UTCTIMESTAMPS:
Log-messages will have timestamps showing the UTC time prepended to
them.
The enumeration LogManipulator is used to handle special or
exceptional situations through manipulators. It is defined in the namespace
FBB and has the following two values:
- FATAL:
This value may be inserted into an FBB::Log object to throw an
FBB::Exception exception (see operator<< below);
- nl:
This value may be inserted into an FBB::Log object to terminate
the current line. It will not cause the next line to begin with a
time stamp (if applicable) and the current message level cannot be
modified using a level(3bobcat) manipulator. It is used to allow a single
log message to occupy multiple textual lines.
- endl:
This is the standard ostream manipulator. When inserted into an
FBB::Log object the current buffer is flushed. Note that flushing does not
happen immediately when a newline (\n) is inserted into the log
stream. Alternatively, std::flush may be inserted into the FBB::Log
object to flush its buffer.
CONSTRUCTORS
- Log():
The default constructor creates a FBB::Log object which isn't yet
associated with a stream to log messages on. The member open (see below)
may be used to define such a stream. By default, all messages will have a
time stamp prepended to them (see the description of the member
setTimestamp below), and a blank space is inserted as delimiter
immediately
beyond the time stamp. The member open can be used to modify the default delimiter.
- Log(std::ostream &out, char const *delim = " "):
This constructor creates a FBB::Log object logging its messages
to the provided std::ostream object. By default, all messages will have a
time stamp prepended to them (see the description of the member
setTimestamp below). The parameter delim is inserted immediately
beyond the time stamp. If a delimiter is inappropriate, an empty string or a
0-pointer may be specified.
- FBB::Log(std::string const &filename,
std::ios::openmode mode = std::ios::out | std::ios::app,
char const *delim = " "):
This constructor creates a FBB::Log object logging its messages to
the named file. If filename == "&1" the logmessages will be written to the
standard output stream. If filename == "&2" the logmessages will be
written to the standard error stream. By default the file is created if not
existing, and all messages are appended to the stream. By default, all
messages will have a time stamp prepended to them (see the description of the
member setTimestamp below). The parameter delim is inserted
immediately beyond the time stamp. If a delimiter is inappropriate, an empty
string or a 0-pointer may be specified.
The copy constructor is not available.
MEMBER FUNCTIONS
All members of std::ostream are available, as FBB::Log inherits
from this class.
- size_t level():
This member returns the currently set log level (i.e., the value set
at the latest setLevel() call). By default, the level is set to zero,
meaning that all information is inserted into the log stream.
- std::ostream &level(size_t useLevel):
This member defines a log-level. Messages will be inserted into
the stream when useLevel is equal to or exceeds the level set by
setLevel. The maximum level which can be selected is
std::numeric_limits<size_t>::max(). If not even such messages should be
inserted into the ostream, then the stream should be deactivated, using
off(), see below. The selected level remains active until
redefined. Alternatively, the FBB::level manipulator may be inserted into
an (empty) FBB::Log object (see level(3bobcat)).
- void off():
Prevents any log messages from being generated. It may be cancelled by
setLevel (see below).
- void open(std::string const &filename,
std::ios::openmode mode = std::ios::out | std::ios::app,
char const *delim = " "):
This member (re)associates an FBB::Log object with the named
file. If filename == "&1" the logmessages will be written to the standard
output stream. If filename == "&2" the logmessages will be written to the
standard error stream. By default the file is created if not existing, and
all messages are appended to the stream. By default, all messages will have a
time stamp prepended to them (see the description of the member
setTimestamp below). The parameter delim is inserted immediately
beyond the time stamp. If a delimiter is inappropriate, an empty string or a
0-pointer may be specified.
- void setLevel(size_t newLevel):
Redefines the internal message level. Messages having at least
level newLevel will be written. If the member is used without explicit
argument, logging is suspended.
- void setTimestamp(FBB::TimeStamps stamp, char const *delim = " "):
The member function (de)activates time stamp prepending. Use the value
FBB::TIMESTAMPS to prepend time stamps, FBB::NOTIMESTAMPS suppresses
time stamps. A timestamp consists of the month, the day number of the month
and the (local) time of the current message, as usually appearing in messages
in /var/log files. E.g., Aug 5 13:52:23. The parameter delim is
inserted immediately beyond the time stamp. If a delimiter is inappropriate,
an empty string or a 0-pointer may be specified. When stamps ==
FBB::NOTIMESTAMPS delim is ignored.
STATIC MEMBERS
- FBB::Log &initialize(std::string const &filename,
std::ios::openmode mode = std::ios::out | std::ios::app,
char const *delim = " "):
Returns a reference to a static FBB::Log object. It may only be
called once, or an FBB::Exception exception is thrown. It associates a
static FBB::Log object with the named file. If filename == "&1" the
logmessages will be written to the standard output stream. If filename ==
"&2" the logmessages will be written to the standard error stream. By
default the file is created if not existing, and all messages are appended to
the stream. By default, all messages will have a time stamp prepended to them
(see the description of the member setTimestamp below). The parameter
delim is inserted immediately beyond the time stamp. If a delimiter is
inappropriate, an empty string or a 0-pointer may be specified.
- FBB::Log &instance():
Returns a reference to a static FBB::Log object, available after
calling Log::initialize. If called before Log::initialize()
an FBB::Exception exception is thrown.
OVERLOADED OPERATOR
The following overloaded operator is defined outside of the FBB
namespace. It may be used to insert an FBB::LogManipulator into an
FBB::Log object. If the overloaded operator is used in combination with
another type of object it performs no actions.
- std::ostream &::operator<<(std::ostream &str, FBB::LogManipulator):
When inserting FBB::FATAL an FBB::Exception exception is thrown;
when inserting FBB::nl the line is terminated, but next insertions will
not start with a time stamp (if applicable).
EXAMPLE
#include <iostream>
#include <iomanip>
#include <bobcat/log>
using namespace std;
using namespace FBB;
int main()
{
// Log &log = Log::initialize("&1");
Log log;
log.open("/tmp/out");
log << "This message is written to cout" << nl <<
setw(16) << ' ' << "occupying multiple lines\n";
log.off();
log << "This message is not shown\n";
log.setLevel(0);
log << "This message is shown again\n";
}
FILES
bobcat/log - defines the class interface
SEE ALSO
bobcat(7), exception(3bobcat), level(3bobcat),
logbuffer(3bobcat)
BUGS
None reported
DISTRIBUTION FILES
- bobcat_4.08.03-x.dsc: detached signature;
- bobcat_4.08.03-x.tar.gz: source archive;
- bobcat_4.08.03-x_i386.changes: change log;
- libbobcat1_4.08.03-x_*.deb: debian package holding the
libraries;
- libbobcat1-dev_4.08.03-x_*.deb: debian package holding the
libraries, headers and manual pages;
- http://sourceforge.net/projects/bobcat: public archive location;
BOBCAT
Bobcat is an acronym of `Brokken's Own Base Classes And Templates'.
COPYRIGHT
This is free software, distributed under the terms of the
GNU General Public License (GPL).
AUTHOR
Frank B. Brokken (f.b.brokken@rug.nl).