DateFormat(3)

NAME
Log::Log4perl::DateFormat - Log4perl advanced date formatter helper class

SYNOPSIS
    use Log::Log4perl::DateFormat;

    my $format = Log::Log4perl::DateFormat->new("HH:mm:ss,SSS");

    # Simple time, resolution in seconds
    my $time = time();
    print $format->format($time), "\n";
        # => "17:02:39,000"

    # Advanced time, resultion in milliseconds
    use Time::HiRes;
    my ($secs, $msecs) = Time::HiRes::gettimeofday();
    print $format->format($secs, $msecs), "\n";
        # => "17:02:39,959"

DESCRIPTION
"Log::Log4perl::DateFormat" is a low-level helper class for the advanced date formatting functions in "Log::Log4perl::Layout::PatternLayout".

Unless you're writing your own Layout class like Log::Log4perl::Layout::PatternLayout, there's probably not much use for you to read this.

"Log::Log4perl::DateFormat" is a formatter which allows dates to be formatted according to the log4j spec on

    http://java.sun.com/j2se/1.5.0/docs/api/java/text/SimpleDateFormat.html

which allows the following placeholders to be recognized and processed:

    Symbol Meaning              Presentation    Example
    ------ -------              ------------    -------
    G      era designator       (Text)          AD
    y      year                 (Number)        1996
    M      month in year        (Text & Number) July & 07
    d      day in month         (Number)        10
    h      hour in am/pm (1~12) (Number)        12
    H      hour in day (0~23)   (Number)        0
    m      minute in hour       (Number)        30
    s      second in minute     (Number)        55
    S      millisecond          (Number)        978
    E      day in week          (Text)          Tuesday
    D      day in year          (Number)        189
    F      day of week in month (Number)        2 (2nd Wed in July)
    w      week in year         (Number)        27
    W      week in month        (Number)        2
    a      am/pm marker         (Text)          PM
    k      hour in day (1~24)   (Number)        24
    K      hour in am/pm (0~11) (Number)        0
    z      time zone            (Text)          Pacific Standard Time
    Z      RFC 822 time zone    (Text)          -0800
    '      escape for text      (Delimiter)
    ''     single quote         (Literal)       '

For example, if you want to format the current Unix time in "MM/dd HH:mm" format, all you have to do is this:

    use Log::Log4perl::DateFormat;

    my $format = Log::Log4perl::DateFormat->new("MM/dd HH:mm");

    my $time = time();
    print $format->format($time), "\n";

While the "new()" method is expensive, because it parses the format strings and sets up all kinds of structures behind the scenes, followup calls to "format()" are fast, because "DateFormat" will just call "localtime()" and "sprintf()" once to return the formatted date/time string.

So, typically, you would initialize the formatter once and then reuse it over and over again to display all kinds of time values.

Also, for your convenience, the following predefined formats are available, just as outlined in the log4j spec:

    Format   Equivalent                     Example
    ABSOLUTE "HH:mm:ss,SSS"                 "15:49:37,459"
    DATE     "dd MMM yyyy HH:mm:ss,SSS"     "06 Nov 1994 15:49:37,459"
    ISO8601  "yyyy-MM-dd HH:mm:ss,SSS"      "1999-11-27 15:49:37,459"
    APACHE   "[EEE MMM dd HH:mm:ss yyyy]"   "[Wed Mar 16 15:49:37 2005]"

So, instead of passing

    Log::Log4perl::DateFormat->new("HH:mm:ss,SSS");

you could just as well say

    Log::Log4perl::DateFormat->new("ABSOLUTE");

and get the same result later on.

  Known Shortcomings
The following placeholders are currently not recognized, unless someone (and that could be you :) implements them:

    F day of week in month
    w week in year
    W week in month
    k hour in day
    K hour in am/pm
    z timezone (but we got 'Z' for the numeric time zone value)

Also, "Log::Log4perl::DateFormat" just knows about English week and month names, internationalization support has to be added.

SEE ALSO

AUTHOR
    Mike Schilli, <log4perl@perlmeister.com>