/usr/share/doc/libbobcat4-dev/man/log.3.html

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<h1 id="title">FBB::Log</h1>
<h2 id="author">libbobcat-dev_4.04.00-x.tar.gz</h2>
<h2 id="date">2005-2016</h2>

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<title>FBB::Log(3bobcat)</title>
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<h1 id="title">FBB::Log(3bobcat)</h1>
<h2 id="author">libbobcat-dev_4.04.00-x.tar.gz Log messages</h2>
<h2 id="date">2005-2016</h2>


<p>
<h2 >NAME</h2>FBB::Log - <em >std::ostream</em> handling log messages
<p>
<h2 >SYNOPSIS</h2>
    <strong >#include &lt;bobcat/log&gt;</strong><br/>
    Linking option: <em >-lbobcat</em> 
<p>
<h2 >DESCRIPTION</h2>
<p>
The class <strong >FBB::Log</strong> is an <em >std::ostream</em> initialized with a
<em >FBB::LogBuffer</em>. It is used to send log-messages to the (r)syslog
stream. Refer to the <strong >logbuffer</strong>(3bobcat) man-page for details about this
process.
<p>
<h2 >NAMESPACE</h2>
    <strong >FBB</strong><br/>
    All constructors, members, operators and manipulators, mentioned in this
man-page, are defined in the namespace <strong >FBB</strong>.
<p>
<h2 >INHERITS FROM</h2>
    <em >std::ostream</em>
<p>
<h2 >ENUMERATIONS</h2>
<p>
The enumeration <em >TimeStamps</em> is defined in the namespace <em >FBB</em>,
primarily for initializing <em >FBB::LogBuffer</em> objects. It is used with
<strong >FBB::Log</strong> members as well. It has the following values:
    <ul>
    <li> <strong >NOTIMESTAMPS</strong>:<br/>
        Log-messages will not have timestamps prepended to them.
    <li> <strong >TIMESTAMPS</strong>:<br/>
        Log-messages will have timestamps prepended to them.
    <li> <strong >UTCTIMESTAMPS</strong>:<br/>
        Log-messages will have timestamps showing the UTC time prepended to
        them.
    </ul>
<p>
The enumeration <em >LogManipulator</em> is used to handle special or
exceptional situations through manipulators. It is defined in the namespace
<em >FBB</em> and has the following two values:
    <ul>
    <li> <strong >FATAL</strong>:<br/>
        This value may be inserted into an <strong >FBB::Log</strong> object to throw an
<em >FBB::Exception</em> exception (see <em >operator&lt;&lt;</em> below);
    <li> <strong >nl</strong>:<br/>
        This value may be inserted into an <strong >FBB::Log</strong> object to terminate
the current line. It will <em >not</em> cause the next line to begin with a
time stamp (if applicable) and the current <em >message level</em> cannot be
modified using a <strong >level</strong>(3bobcat) manipulator. It is used to allow a single 
log message to occupy multiple textual lines.
    <li> <strong >endl</strong>:<br/>
        This is the standard <em >ostream</em> manipulator. When inserted into an
<strong >FBB::Log</strong> object the current buffer is flushed. Note that flushing does not
happen immediately when a newline (<em >\n</em>) is inserted into the log
stream. Alternatively, <em >std::flush</em> may be inserted into the <strong >FBB::Log</strong>
object to flush its buffer.
    </ul>
<p>
<h2 >CONSTRUCTORS</h2>
    <ul>
    <li> <strong >Log()</strong>:<br/>
        The default constructor creates a <strong >FBB::Log</strong> object which isn't yet
associated with a stream to log messages on. The member <em >open</em> (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
<em >setTimestamp</em> below), and a blank space is inserted as delimiter 
immediately
beyond the time stamp. The member <em >open</em> can be used to modify the default delimiter.
    <li> <strong >Log(std::ostream &amp;out, char const *delim = " ")</strong>:<br/>
        This constructor creates a <strong >FBB::Log</strong> object logging its messages
to the provided <em >std::ostream</em> object. By default, all messages will have a
time stamp prepended to them (see the description of the member
<em >setTimestamp</em> below).  The parameter <em >delim</em> is inserted immediately
beyond the time stamp. If a delimiter is inappropriate, an empty string or a
0-pointer may be specified.
    <li> <strong >FBB::Log(std::string const &amp;filename,
            std::ios::openmode mode = std::ios::out | std::ios::app, 
            char const *delim = " ")</strong>:<br/>
        This constructor creates a <strong >FBB::Log</strong> object logging its messages to
the named file. If <em >filename == "&amp;1"</em> the logmessages will be written to the
standard output stream. If <em >filename == "&amp;2"</em> 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 <em >setTimestamp</em> below).  The parameter <em >delim</em> is inserted
immediately beyond the time stamp. If a delimiter is inappropriate, an empty
string or a 0-pointer may be specified.
    </ul>
    The copy constructor is not available.
<p>
<h2 >MEMBER FUNCTIONS</h2>
     All members of <em >std::ostream</em> are available, as <strong >FBB::Log</strong> inherits
from this class.
    <ul>
    <li> <strong >size_t level()</strong>:<br/>
        This member returns the currently set log level (i.e., the value set
at the latest <em >setLevel()</em> call). By default, the level is set to zero,
meaning that all information is inserted into the log stream.
    <li> <strong >std::ostream &amp;level(size_t useLevel)</strong>:<br/>
        This member defines a log-level. Messages will be inserted into
the stream when <em >useLevel</em> is equal to or exceeds the level set by
    <em >setLevel</em>. The maximum level which can be selected is
<em >std::numeric_limits&lt;size_t&gt;::max()</em>. If not even such messages should be
inserted into the <em >ostream</em>, then the stream should be deactivated, using
<em >off()</em>, see below. The selected level remains active until
redefined. Alternatively, the <em >FBB::level</em> manipulator may be inserted into
an (empty) <strong >FBB::Log</strong> object (see <strong >level</strong>(3bobcat)).
    <li> <strong >void off()</strong>:<br/>
        Prevents any log messages from being generated. It may be cancelled by
<em >setLevel</em> (see below).
    <li> <strong >void open(std::string const &amp;filename,
            std::ios::openmode mode = std::ios::out | std::ios::app, 
            char const *delim = " ")</strong>:<br/>
        This member (re)associates an <strong >FBB::Log</strong> object with the named
file. If <em >filename == "&amp;1"</em> the logmessages will be written to the standard
output stream. If <em >filename == "&amp;2"</em> 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
<em >setTimestamp</em> below).  The parameter <em >delim</em> is inserted immediately
beyond the time stamp. If a delimiter is inappropriate, an empty string or a
0-pointer may be specified.
    <li> <strong >void setLevel(size_t newLevel)</strong>:<br/>
        Redefines the internal message level. Messages having at least
level <em >newLevel</em> will be written. If the member is used without explicit
argument, logging is suspended.
    <li> <strong >void setTimestamp(FBB::TimeStamps stamp, char const *delim = " ")</strong>:<br/>
        The member function (de)activates time stamp prepending. Use the value
<em >FBB::TIMESTAMPS</em> to prepend time stamps, <em >FBB::NOTIMESTAMPS</em> 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 <em >/var/log</em> files. E.g., <em >Aug 5 13:52:23</em>. The parameter <em >delim</em> is
inserted immediately beyond the time stamp. If a delimiter is inappropriate,
an empty string or a 0-pointer may be specified. When <em >stamps ==
FBB::NOTIMESTAMPS delim</em> is ignored.
    </ul>
<p>
<h2 >STATIC MEMBERS</h2>
    <ul>
    <li> <strong >FBB::Log &amp;initialize(std::string const &amp;filename,
            std::ios::openmode mode = std::ios::out | std::ios::app, 
            char const *delim = " ")</strong>:<br/>
<p>
Returns a reference to a static <strong >FBB::Log</strong> object. It may only be
called once, or an <em >FBB::Exception</em> exception is thrown. It associates a
static <strong >FBB::Log</strong> object with the named file. If <em >filename == "&amp;1"</em> the
logmessages will be written to the standard output stream. If <em >filename ==
"&amp;2"</em> 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 <em >setTimestamp</em> below).  The parameter
<em >delim</em> is inserted immediately beyond the time stamp. If a delimiter is
inappropriate, an empty string or a 0-pointer may be specified.
    <li> <strong >FBB::Log &amp;instance()</strong>:<br/>
        Returns a reference to a static <strong >FBB::Log</strong> object, available after
calling <em >Log::initialize</em>. If called before <em >Log::initialize()</em>
an <em >FBB::Exception</em> exception is thrown. 
    </ul>
<p>
<h2 >OVERLOADED OPERATOR</h2>
    The following overloaded operator is defined outside of the <em >FBB</em>
namespace. It may be used to insert an <em >FBB::LogManipulator</em> into an
<strong >FBB::Log</strong> object. If the overloaded operator is used in combination with
another type of object it performs no actions.
    <ul>
    <li> <strong >std::ostream &amp;::operator&lt;&lt;(std::ostream &amp;str, FBB::LogManipulator)</strong>:<br/> 
        When inserting <em >FBB::FATAL</em> an <em >FBB::Exception</em> exception is thrown;
when inserting <em >FBB::nl</em> the line is terminated, but next insertions will
not start with a time stamp (if applicable). 
    </ul>
<p>
<h2 >EXAMPLE</h2>
    <pre >
#include &lt;iostream&gt;
#include &lt;iomanip&gt;

#include &lt;bobcat/log&gt;

using namespace std;
using namespace FBB;

int main()
{
//    Log &amp;log = Log::initialize("&amp;1");
    Log log;
    log.open("/tmp/out");

    log &lt;&lt; "This message is written to cout" &lt;&lt; nl &lt;&lt;
           setw(16) &lt;&lt; ' ' &lt;&lt; "occupying multiple lines\n";

    log.off();
    log &lt;&lt; "This message is not shown\n";
    log.setLevel(0);
    log &lt;&lt; "This message is shown again\n";
}


</pre>

<p>
<h2 >FILES</h2>
    <em >bobcat/log</em> - defines the class interface
<p>
<h2 >SEE ALSO</h2>
    <strong >bobcat</strong>(7), <strong >exception</strong>(3bobcat), <strong >level</strong>(3bobcat),
    <strong >logbuffer</strong>(3bobcat)
<p>
<h2 >BUGS</h2>
    None reported
<p>

<h2 >DISTRIBUTION FILES</h2>
    <ul>
    <li> <em >bobcat_4.04.00-x.dsc</em>: detached signature;
    <li> <em >bobcat_4.04.00-x.tar.gz</em>: source archive;
    <li> <em >bobcat_4.04.00-x_i386.changes</em>: change log;
    <li> <em >libbobcat1_4.04.00-x_*.deb</em>: debian package holding the
            libraries;
    <li> <em >libbobcat1-dev_4.04.00-x_*.deb</em>: debian package holding the
            libraries, headers and manual pages;
    <li> <em >http://sourceforge.net/projects/bobcat</em>: public archive location;
    </ul>
<p>
<h2 >BOBCAT</h2>
    Bobcat is an acronym of `Brokken's Own Base Classes And Templates'.
<p>
<h2 >COPYRIGHT</h2>
    This is free software, distributed under the terms of the 
    GNU General Public License (GPL).
<p>
<h2 >AUTHOR</h2>
    Frank B. Brokken (<strong >f.b.brokken@rug.nl</strong>).
<p>
libbobcat-dev 4.04.00-1 / usr / share / doc / libbobcat4-dev / man / log.3.html
