log::message.3

视频监控网络部分的协议ddns,的模块的实现代码,请大家大胆指正.

.\" Automatically generated by Pod::Man 2.16 (Pod::Simple 3.05)
.\"
.\" Standard preamble:
.\" ========================================================================
.de Sh \" Subsection heading
.br
.if t .Sp
.ne 5
.PP
\fB\\$1\fR
.PP
..
.de Sp \" Vertical space (when we can't use .PP)
.if t .sp .5v
.if n .sp
..
.de Vb \" Begin verbatim text
.ft CW
.nf
.ne \\$1
..
.de Ve \" End verbatim text
.ft R
.fi
..
.\" Set up some character translations and predefined strings.  \*(-- will
.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
.\" double quote, and \*(R" will give a right double quote.  \*(C+ will
.\" give a nicer C++.  Capital omega is used to do unbreakable dashes and
.\" therefore won't be available.  \*(C` and \*(C' expand to `' in nroff,
.\" nothing in troff, for use with C<>.
.tr \(*W-
.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
.ie n \{\
.    ds -- \(*W-
.    ds PI pi
.    if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
.    if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\"  diablo 12 pitch
.    ds L" ""
.    ds R" ""
.    ds C` ""
.    ds C' ""
'br\}
.el\{\
.    ds -- \|\(em\|
.    ds PI \(*p
.    ds L" ``
.    ds R" ''
'br\}
.\"
.\" Escape single quotes in literal strings from groff's Unicode transform.
.ie \n(.g .ds Aq \(aq
.el       .ds Aq '
.\"
.\" If the F register is turned on, we'll generate index entries on stderr for
.\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index
.\" entries marked with X<> in POD.  Of course, you'll have to process the
.\" output yourself in some meaningful fashion.
.ie \nF \{\
.    de IX
.    tm Index:\\$1\t\\n%\t"\\$2"
..
.    nr % 0
.    rr F
.\}
.el \{\
.    de IX
..
.\}
.\"
.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
.\" Fear.  Run.  Save yourself.  No user-serviceable parts.
.    \" fudge factors for nroff and troff
.if n \{\
.    ds #H 0
.    ds #V .8m
.    ds #F .3m
.    ds #[ \f1
.    ds #] \fP
.\}
.if t \{\
.    ds #H ((1u-(\\\\n(.fu%2u))*.13m)
.    ds #V .6m
.    ds #F 0
.    ds #[ \&
.    ds #] \&
.\}
.    \" simple accents for nroff and troff
.if n \{\
.    ds ' \&
.    ds ` \&
.    ds ^ \&
.    ds , \&
.    ds ~ ~
.    ds /
.\}
.if t \{\
.    ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
.    ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
.    ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
.    ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
.    ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
.    ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
.\}
.    \" troff and (daisy-wheel) nroff accents
.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
.ds 8 \h'\*(#H'\(*b\h'-\*(#H'
.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
.ds ae a\h'-(\w'a'u*4/10)'e
.ds Ae A\h'-(\w'A'u*4/10)'E
.    \" corrections for vroff
.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
.    \" for low resolution devices (crt and lpr)
.if \n(.H>23 .if \n(.V>19 \
\{\
.    ds : e
.    ds 8 ss
.    ds o a
.    ds d- d\h'-1'\(ga
.    ds D- D\h'-1'\(hy
.    ds th \o'bp'
.    ds Th \o'LP'
.    ds ae ae
.    ds Ae AE
.\}
.rm #[ #] #H #V #F C
.\" ========================================================================
.\"
.IX Title "Log::Message 3"
.TH Log::Message 3 "2007-12-18" "perl v5.10.0" "Perl Programmers Reference Guide"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
Log::Message \- A generic message storing mechanism;
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\&    use Log::Message private => 0, config => \*(Aq/our/cf_file\*(Aq;
\&
\&    my $log = Log::Message\->new(    private => 1,
\&                                    level   => \*(Aqlog\*(Aq,
\&                                    config  => \*(Aq/my/cf_file\*(Aq,
\&                               );
\&
\&    $log\->store(\*(Aqthis is my first message\*(Aq);
\&
\&    $log\->store(    message => \*(Aqmessage #2\*(Aq,
\&                    tag     => \*(AqMY_TAG\*(Aq,
\&                    level   => \*(Aqcarp\*(Aq,
\&                    extra   => [\*(Aqthis is an argument to the handler\*(Aq],
\&               );
\&
\&    my @last_five_items = $log\->retrieve(5);
\&
\&    my @items = $log\->retrieve( tag     => qr/my_tag/i,
\&                                message => qr/\ed/,
\&                                remove  => 1,
\&                              );
\&
\&    my @items = $log\->final( level => qr/carp/, amount => 2 );
\&
\&    my $first_error = $log\->first()
\&
\&    # croak with the last error on the stack
\&    $log\->final\->croak;
\&
\&    # empty the stack
\&    $log\->flush();
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
Log::Message is a generic message storage mechanism.
It allows you to store messages on a stack \*(-- either shared or private
\&\*(-- and assign meta-data to it.
Some meta-data will automatically be added for you, like a timestamp
and a stack trace, but some can be filled in by the user, like a tag
by which to identify it or group it, and a level at which to handle
the message (for example, log it, or die with it)
.PP
Log::Message also provides a powerful way of searching through items
by regexes on messages, tags and level.
.SH "Hierarchy"
.IX Header "Hierarchy"
There are 4 modules of interest when dealing with the Log::Message::*
modules:
.IP "Log::Message" 4
.IX Item "Log::Message"
Log::Message provides a few methods to manipulate the stack it keeps.
It has the option of keeping either a private or a public stack.
More on this below.
.IP "Log::Message::Item" 4
.IX Item "Log::Message::Item"
These are individual message items, which are objects that contain
the user message as well as the meta-data described above.
See the Log::Message::Item manpage to see how to extract this 
meta-data and how to work with the Item objects.
You should never need to create your own Item objects, but knowing
about their methods and accessors is important if you want to write
your own handlers. (See below)
.IP "Log::Message::Handlers" 4
.IX Item "Log::Message::Handlers"
These are a collection of handlers that will be called for a level
that is used on a Log::Message::Item object.
For example, if a message is logged with the 'carp' level, the 'carp'
handler from Log::Message::Handlers will be called.
See the Log::Message::Handlers manpage for more explanation about how
handlers work, which one are available and how to create your own.
.IP "Log::Message::Config" 4
.IX Item "Log::Message::Config"
Per Log::Message object, there is a configuration required that will
fill in defaults if the user did not specify arguments to override
them (like for example what tag will be set if none was provided),
Log::Message::Config handles the creation of these configurations.
.Sp
Configuration can be specified in 4 ways:
.RS 4
.IP "\(bu" 4
As a configuration file when you \f(CW\*(C`use Log::Message\*(C'\fR
.IP "\(bu" 4
As arguments when you \f(CW\*(C`use Log::Message\*(C'\fR
.IP "\(bu" 4
As a configuration file when you create a new Log::Message object.
(The config will then only apply to that object if you marked it as
private)
.IP "\(bu" 4
As arguments when you create a new Log::Message object.
.Sp
You should never need to use the Log::Message::Config module yourself,
as this is transparently done by Log::Message, but its manpage does
provide an explanation of how you can create a config file.
.RE
.RS 4
.RE
.SH "Options"
.IX Header "Options"
When using Log::Message, or creating a new Log::Message object, you can
supply various options to alter its behaviour.
Of course, there are sensible defaults should you choose to omit these
options.
.PP
Below an explanation of all the options and how they work.
.IP "config" 4
.IX Item "config"
The path to a configuration file to be read.
See the manpage of Log::Message::Config for the required format
.Sp
These options will be overridden by any explicit arguments passed.
.IP "private" 4
.IX Item "private"
Whether to create, by default, private or shared objects.
If you choose to create shared objects, all Log::Message objects will
use the same stack.
.Sp
This means that even though every module may make its own \f(CW$log\fR object
they will still be sharing the same error stack on which they are
putting errors and from which they are retrieving.
.Sp
This can be useful in big projects.
.Sp
If you choose to create a private object, then the stack will of
course be private to this object, but it will still fall back to the
shared config should no private config or overriding arguments be
provided.
.IP "verbose" 4
.IX Item "verbose"
Log::Message makes use of another module to validate its arguments,
which is called Params::Check, which is a lightweight, yet 
powerful input checker and parser. (See the Params::Check 
manpage for details).
.Sp
The verbose setting will control whether this module will
generate warnings if something improper is passed as input, or merely
silently returns undef, at which point Log::Message will generate a
warning.
.Sp
It's best to just leave this at its default value, which is '1'
.IP "tag" 4
.IX Item "tag"
The tag to add to messages if none was provided. If neither your
config, nor any specific arguments supply a tag, then Log::Message will
set it to '\s-1NONE\s0'
.Sp
Tags are useful for searching on or grouping by. For example, you
could tag all the messages you want to go to the user as '\s-1USER\s0 \s-1ERROR\s0'
and all those that are only debug information with '\s-1DEBUG\s0'.
.Sp
At the end of your program, you could then print all the ones tagged
\&'\s-1USER\s0 \s-1ERROR\s0' to \s-1STDOUT\s0, and those marked '\s-1DEBUG\s0' to a log file.
.IP "level" 4
.IX Item "level"
\&\f(CW\*(C`level\*(C'\fR describes what action to take when a message is logged. Just
like \f(CW\*(C`tag\*(C'\fR, Log::Message will provide a default (which is 'log') if
neither your config file, nor any explicit arguments are given to
override it.
.Sp
See the Log::Message::Handlers manpage to see what handlers are
available by default and what they do, as well as to how to add your
own handlers.
.IP "remove" 4
.IX Item "remove"
This indicates whether or not to automatically remove the messages
from the stack when you've retrieved them.
The default setting provided by Log::Message is '0': do not remove.
.IP "chrono" 4
.IX Item "chrono"
This indicates whether messages should always be fetched in
chronological order or not.
This simply means that you can choose whether, when retrieving items,
the item most recently added should be returned first, or the one that
had been added most long ago.
.Sp
The default is to return the newest ones first
.SH "Methods"
.IX Header "Methods"
.Sh "new"
.IX Subsection "new"
This creates a new Log::Message object; The parameters it takes are
described in the \f(CW\*(C`Options\*(C'\fR section below and let it just be repeated
that you can use these options like this:
.PP
.Vb 1
\&    my $log = Log::Message\->new( %options );
.Ve
.PP
as well as during \f(CW\*(C`use\*(C'\fR time, like this:
.PP
.Vb 1
\&    use Log::Message option1 => value, option2 => value
.Ve
.PP
There are but 3 rules to keep in mind:
.IP "\(bu" 4
Provided arguments take precedence over a configuration file.
.IP "\(bu" 4
Arguments to new take precedence over options provided at \f(CW\*(C`use\*(C'\fR time
.IP "\(bu" 4
An object marked private will always have an empty stack to begin with
.Sh "store"
.IX Subsection "store"
This will create a new Item object and store it on the stack.
.PP
Possible arguments you can give to it are:
.IP "message" 4
.IX Item "message"
This is the only argument that is required. If no other arguments
are given, you may even leave off the \f(CW\*(C`message\*(C'\fR key. The argument
will then automatically be assumed to be the message.
.IP "tag" 4
.IX Item "tag"
The tag to add to this message. If not provided, Log::Message will look
in your configuration for one.
.IP "level" 4
.IX Item "level"
The level at which this message should be handled. If not provided,
Log::Message will look in your configuration for one.
.IP "extra" 4
.IX Item "extra"
This is an array ref with arguments passed to the handler for this
message, when it is called from \fIstore()\fR;
.Sp
The handler will receive them as a normal list
.PP
\&\fIstore()\fR will return true upon success and undef upon failure, as well
as issue a warning as to why it failed.
.Sh "retrieve"
.IX Subsection "retrieve"
This will retrieve all message items matching the criteria specified
from the stack.
.PP
Here are the criteria you can discriminate on:
.IP "tag" 4
.IX Item "tag"
A regex to which the tag must adhere. For example \f(CW\*(C`qr/\ew/\*(C'\fR.
.IP "level" 4
.IX Item "level"
A regex to which the level must adhere.
.IP "message" 4
.IX Item "message"
A regex to which the message must adhere.
.IP "amount" 4
.IX Item "amount"
Maximum amount of errors to return
.IP "chrono" 4
.IX Item "chrono"
Return in chronological order, or not?
.IP "remove" 4
.IX Item "remove"
Remove items from the stack upon retrieval?
.PP
In scalar context it will return the first item matching your criteria
and in list context, it will return all of them.
.PP
If an error occurs while retrieving, a warning will be issued and
undef will be returned.
.Sh "first"
.IX Subsection "first"
This is a shortcut for retrieving the first item(s) stored on the
stack. It will default to only retrieving one if called with no
arguments, and will always return results in chronological order.
.PP
If you only supply one argument, it is assumed to be the amount you
wish returned.
.PP
Furthermore, it can take the same arguments as \f(CW\*(C`retrieve\*(C'\fR can.
.Sh "last"
.IX Subsection "last"
This is a shortcut for retrieving the last item(s) stored on the
stack. It will default to only retrieving one if called with no
arguments, and will always return results in reverse chronological
order.
.PP
If you only supply one argument, it is assumed to be the amount you
wish returned.
.PP
Furthermore, it can take the same arguments as \f(CW\*(C`retrieve\*(C'\fR can.
.Sh "flush"
.IX Subsection "flush"
This removes all items from the stack and returns them to the caller
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Log::Message::Item, Log::Message::Handlers, Log::Message::Config
.SH "AUTHOR"
.IX Header "AUTHOR"
This module by
Jos Boumans <[e-mail]>.
.SH "Acknowledgements"
.IX Header "Acknowledgements"
Thanks to Ann Barcomb for her suggestions.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
This module is
copyright (c) 2002 Jos Boumans <[e-mail]>.
All rights reserved.
.PP
This library is free software;
you may redistribute and/or modify it under the same
terms as Perl itself.