yaml.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.

.PP
The current options are:
.IP "DumperClass" 4
.IX Item "DumperClass"
You can override which module/class \s-1YAML\s0 uses for Dumping data.
.IP "LoaderClass" 4
.IX Item "LoaderClass"
You can override which module/class \s-1YAML\s0 uses for Loading data.
.IP "Indent" 4
.IX Item "Indent"
This is the number of space characters to use for each indentation level
when doing a \fIDump()\fR. The default is 2.
.Sp
By the way, \s-1YAML\s0 can use any number of characters for indentation at any
level. So if you are editing \s-1YAML\s0 by hand feel free to do it anyway that
looks pleasing to you; just be consistent for a given level.
.IP "SortKeys" 4
.IX Item "SortKeys"
Default is 1. (true)
.Sp
Tells \s-1YAML\s0.pm whether or not to sort hash keys when storing a document.
.Sp
YAML::Node objects can have their own sort order, which is usually what
you want. To override the YAML::Node order and sort the keys anyway, set
SortKeys to 2.
.IP "Stringify" 4
.IX Item "Stringify"
Default is 0. (false)
.Sp
Objects with string overloading should honor the overloading and dump the
stringification of themselves, rather than the actual object's guts.
.IP "UseHeader" 4
.IX Item "UseHeader"
Default is 1. (true)
.Sp
This tells \s-1YAML\s0.pm whether to use a separator string for a Dump
operation. This only applies to the first document in a stream.
Subsequent documents must have a \s-1YAML\s0 header by definition.
.IP "UseVersion" 4
.IX Item "UseVersion"
Default is 0. (false)
.Sp
Tells \s-1YAML\s0.pm whether to include the \s-1YAML\s0 version on the
separator/header.
.Sp
.Vb 1
\&    \-\-\- %YAML:1.0
.Ve
.IP "AnchorPrefix" 4
.IX Item "AnchorPrefix"
Default is ''.
.Sp
Anchor names are normally numeric. \s-1YAML\s0.pm simply starts with '1' and
increases by one for each new anchor. This option allows you to specify a
string to be prepended to each anchor number.
.IP "UseCode" 4
.IX Item "UseCode"
Setting the UseCode option is a shortcut to set both the DumpCode and
LoadCode options at once. Setting UseCode to '1' tells \s-1YAML\s0.pm to dump
Perl code references as Perl (using B::Deparse) and to load them back
into memory using \fIeval()\fR. The reason this has to be an option is that
using \fIeval()\fR to parse untrusted code is, well, untrustworthy.
.IP "DumpCode" 4
.IX Item "DumpCode"
Determines if and how \s-1YAML\s0.pm should serialize Perl code references. By
default \s-1YAML\s0.pm will dump code references as dummy placeholders (much
like Data::Dumper). If DumpCode is set to '1' or 'deparse', code
references will be dumped as actual Perl code.
.Sp
DumpCode can also be set to a subroutine reference so that you can
write your own serializing routine. \s-1YAML\s0.pm passes you the code ref. You
pass back the serialization (as a string) and a format indicator. The
format indicator is a simple string like: 'deparse' or 'bytecode'.
.IP "LoadCode" 4
.IX Item "LoadCode"
LoadCode is the opposite of DumpCode. It tells \s-1YAML\s0 if and how to
deserialize code references. When set to '1' or 'deparse' it will use
\&\f(CW\*(C`eval()\*(C'\fR. Since this is potentially risky, only use this option if you
know where your \s-1YAML\s0 has been.
.Sp
LoadCode can also be set to a subroutine reference so that you can write
your own deserializing routine. \s-1YAML\s0.pm passes the serialization (as a
string) and a format indicator. You pass back the code reference.
.IP "UseBlock" 4
.IX Item "UseBlock"
\&\s-1YAML\s0.pm uses heuristics to guess which scalar style is best for a given
node. Sometimes you'll want all multiline scalars to use the 'block'
style. If so, set this option to 1.
.Sp
\&\s-1NOTE:\s0 \s-1YAML\s0's block style is akin to Perl's here-document.
.IP "UseFold" 4
.IX Item "UseFold"
If you want to force \s-1YAML\s0 to use the 'folded' style for all multiline
scalars, then set \f(CW$UseFold\fR to 1.
.Sp
\&\s-1NOTE:\s0 \s-1YAML\s0's folded style is akin to the way \s-1HTML\s0 folds text,
      except smarter.
.IP "UseAliases" 4
.IX Item "UseAliases"
\&\s-1YAML\s0 has an alias mechanism such that any given structure in memory gets
serialized once. Any other references to that structure are serialized
only as alias markers. This is how \s-1YAML\s0 can serialize duplicate and
recursive structures.
.Sp
Sometimes, when you \s-1KNOW\s0 that your data is nonrecursive in nature, you
may want to serialize such that every node is expressed in full. (ie as
a copy of the original). Setting \f(CW$YAML::UseAliases\fR to 0 will allow you
to do this. This also may result in faster processing because the lookup
overhead is by bypassed.
.Sp
\&\s-1THIS\s0 \s-1OPTION\s0 \s-1CAN\s0 \s-1BE\s0 \s-1DANGEROUS\s0. *If* your data is recursive, this option
*will* cause \fIDump()\fR to run in an endless loop, chewing up your computers
memory. You have been warned.
.IP "CompressSeries" 4
.IX Item "CompressSeries"
Default is 1.
.Sp
Compresses the formatting of arrays of hashes:
.Sp
.Vb 4
\&    \-
\&      foo: bar
\&    \- 
\&      bar: foo
.Ve
.Sp
becomes:
.Sp
.Vb 2
\&    \- foo: bar
\&    \- bar: foo
.Ve
.Sp
Since this output is usually more desirable, this option is turned on by
default.
.SH "YAML TERMINOLOGY"
.IX Header "YAML TERMINOLOGY"
\&\s-1YAML\s0 is a full featured data serialization language, and thus has its
own terminology.
.PP
It is important to remember that although \s-1YAML\s0 is heavily influenced by
Perl and Python, it is a language in its own right, not merely just a
representation of Perl structures.
.PP
\&\s-1YAML\s0 has three constructs that are conspicuously similar to Perl's hash,
array, and scalar. They are called mapping, sequence, and string
respectively. By default, they do what you would expect. But each
instance may have an explicit or implicit tag (type) that makes it
behave differently. In this manner, \s-1YAML\s0 can be extended to represent
Perl's Glob or Python's tuple, or Ruby's Bigint.
.IP "stream" 4
.IX Item "stream"
A \s-1YAML\s0 stream is the full sequence of unicode characters that a \s-1YAML\s0
parser would read or a \s-1YAML\s0 emitter would write. A stream may contain
one or more \s-1YAML\s0 documents separated by \s-1YAML\s0 headers.
.Sp
.Vb 6
\&    \-\-\-
\&    a: mapping
\&    foo: bar
\&    \-\-\-
\&    \- a
\&    \- sequence
.Ve
.IP "document" 4
.IX Item "document"
A \s-1YAML\s0 document is an independent data structure representation within a
stream. It is a top level node. Each document in a \s-1YAML\s0 stream must
begin with a \s-1YAML\s0 header line. Actually the header is optional on the
first document.
.Sp
.Vb 6
\&    \-\-\-
\&    This: top level mapping
\&    is:
\&        \- a
\&        \- YAML
\&        \- document
.Ve
.IP "header" 4
.IX Item "header"
A \s-1YAML\s0 header is a line that begins a \s-1YAML\s0 document. It consists of
three dashes, possibly followed by more info. Another purpose of the
header line is that it serves as a place to put top level tag and anchor
information.
.Sp
.Vb 3
\&    \-\-\- !recursive\-sequence &001
\&    \- * 001
\&    \- * 001
.Ve
.IP "node" 4
.IX Item "node"
A \s-1YAML\s0 node is the representation of a particular data stucture. Nodes
may contain other nodes. (In Perl terms, nodes are like scalars.
Strings, arrayrefs and hashrefs. But this refers to the serialized
format, not the in-memory structure.)
.IP "tag" 4
.IX Item "tag"
This is similar to a type. It indicates how a particular \s-1YAML\s0 node
serialization should be transferred into or out of memory. For instance
a Foo::Bar object would use the tag 'perl/Foo::Bar':
.Sp
.Vb 3
\&    \- !perl/Foo::Bar
\&        foo: 42
\&        bar: stool
.Ve
.IP "collection" 4
.IX Item "collection"
A collection is the generic term for a \s-1YAML\s0 data grouping. \s-1YAML\s0 has two
types of collections: mappings and sequences. (Similar to hashes and arrays)
.IP "mapping" 4
.IX Item "mapping"
A mapping is a \s-1YAML\s0 collection defined by unordered key/value pairs with
unique keys. By default \s-1YAML\s0 mappings are loaded into Perl hashes.
.Sp
.Vb 3
\&    a mapping:
\&        foo: bar
\&        two: times two is 4
.Ve
.IP "sequence" 4
.IX Item "sequence"
A sequence is a \s-1YAML\s0 collection defined by an ordered list of elements. By
default \s-1YAML\s0 sequences are loaded into Perl arrays.
.Sp
.Vb 4
\&    a sequence:
\&        \- one bourbon
\&        \- one scotch
\&        \- one beer
.Ve
.IP "scalar" 4
.IX Item "scalar"
A scalar is a \s-1YAML\s0 node that is a single value. By default \s-1YAML\s0 scalars
are loaded into Perl scalars.
.Sp
.Vb 1
\&    a scalar key: a scalar value
.Ve
.Sp
\&\s-1YAML\s0 has many styles for representing scalars. This is important because
varying data will have varying formatting requirements to retain the
optimum human readability.
.IP "plain scalar" 4
.IX Item "plain scalar"
A plain sclar is unquoted. All plain scalars are automatic candidates
for \*(L"implicit tagging\*(R". This means that their tag may be determined
automatically by examination. The typical uses for this are plain alpha
strings, integers, real numbers, dates, times and currency.
.Sp
.Vb 5
\&    \- a plain string
\&    \- \-42
\&    \- 3.1415
\&    \- 12:34
\&    \- 123 this is an error
.Ve
.IP "single quoted scalar" 4
.IX Item "single quoted scalar"
This is similar to Perl's use of single quotes. It means no escaping
except for single quotes which are escaped by using two adjacent
single quotes.
.Sp
.Vb 1
\&    \- \*(AqWhen I say \*(Aq\*(Aq\en\*(Aq\*(Aq I mean "backslash en"\*(Aq
.Ve
.IP "double quoted scalar" 4
.IX Item "double quoted scalar"
This is similar to Perl's use of double quotes. Character escaping can
be used.
.Sp
.Vb 1
\&    \- "This scalar\enhas two lines, and a bell \-\->\ea"
.Ve
.IP "folded scalar" 4
.IX Item "folded scalar"
This is a multiline scalar which begins on the next line. It is
indicated by a single right angle bracket. It is unescaped like the
single quoted scalar. Line folding is also performed.
.Sp
.Vb 6
\&    \- > 
\&     This is a multiline scalar which begins on
\&     the next line. It is indicated by a single
\&     carat. It is unescaped like the single
\&     quoted scalar. Line folding is also
\&     performed.
.Ve
.IP "block scalar" 4
.IX Item "block scalar"
This final multiline form is akin to Perl's here-document except that
(as in all \s-1YAML\s0 data) scope is indicated by indentation. Therefore, no
ending marker is required. The data is verbatim. No line folding.
.Sp
.Vb 5
\&    \- |
\&        QTY  DESC          PRICE  TOTAL
\&        \-\-\-  \-\-\-\-          \-\-\-\-\-  \-\-\-\-\-
\&          1  Foo Fighters  $19.95 $19.95
\&          2  Bar Belles    $29.95 $59.90
.Ve
.IP "parser" 4
.IX Item "parser"
A \s-1YAML\s0 processor has four stages: parse, load, dump, emit.
.Sp
A parser parses a \s-1YAML\s0 stream. \s-1YAML\s0.pm's \fILoad()\fR function contains a
parser.
.IP "loader" 4
.IX Item "loader"
The other half of the \fILoad()\fR function is a loader. This takes the
information from the parser and loads it into a Perl data structure.
.IP "dumper" 4
.IX Item "dumper"
The \fIDump()\fR function consists of a dumper and an emitter. The dumper
walks through each Perl data structure and gives info to the emitter.
.IP "emitter" 4
.IX Item "emitter"
The emitter takes info from the dumper and turns it into a \s-1YAML\s0 stream.
.Sp
\&\s-1NOTE:\s0 
In \s-1YAML\s0.pm the parser/loader and the dumper/emitter code are currently
very closely tied together. In the future they may be broken into
separate stages.
.PP
For more information please refer to the immensely helpful \s-1YAML\s0
specification available at <http://www.yaml.org/spec/>.
.SH "ysh \- The YAML Shell"
.IX Header "ysh - The YAML Shell"
The \s-1YAML\s0 distribution ships with a script called 'ysh', the \s-1YAML\s0 shell.
ysh provides a simple, interactive way to play with \s-1YAML\s0. If you type in
Perl code, it displays the result in \s-1YAML\s0. If you type in \s-1YAML\s0 it turns
it into Perl code.
.PP
To run ysh, (assuming you installed it along with \s-1YAML\s0.pm) simply type:
.PP
.Vb 1
\&    ysh [options]
.Ve
.PP
Please read the \f(CW\*(C`ysh\*(C'\fR documentation for the full details. There are
lots of options.
.SH "BUGS & DEFICIENCIES"
.IX Header "BUGS & DEFICIENCIES"
If you find a bug in \s-1YAML\s0, please try to recreate it in the \s-1YAML\s0 Shell
with logging turned on ('ysh \-L'). When you have successfully reproduced
the bug, please mail the \s-1LOG\s0 file to the author ([e-mail]).
.PP
\&\s-1WARNING:\s0 This is still *ALPHA* code. Well, most of this code has been
around for years...
.PP
\&\s-1BIGGER\s0 \s-1WARNING:\s0 \s-1YAML\s0.pm has been slow in the making, but I am committed
to having top notch \s-1YAML\s0 tools in the Perl world. The \s-1YAML\s0 team is close
to finalizing the \s-1YAML\s0 1.1 spec. This version of \s-1YAML\s0.pm is based off of
a very old pre 1.0 spec. In actuality there isn't a ton of difference,
and this \s-1YAML\s0.pm is still fairly useful. Things will get much better in
the future.
.SH "RESOURCES"
.IX Header "RESOURCES"
<http://lists.sourceforge.net/lists/listinfo/yaml\-core> is the mailing
list. This is where the language is discussed and designed.
.PP
<http://www.yaml.org> is the official \s-1YAML\s0 website.
.PP
<http://www.yaml.org/spec/> is the \s-1YAML\s0 1.0 specification.
.PP
<http://yaml.kwiki.org> is the official \s-1YAML\s0 wiki.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
See YAML::Syck. Fast!
.SH "AUTHOR"
.IX Header "AUTHOR"
Ingy dA\*~Xt Net <[e-mail]>
.PP
is resonsible for \s-1YAML\s0.pm.
.PP
The \s-1YAML\s0 serialization language is the result of years of collaboration
between Oren Ben-Kiki, Clark Evans and Ingy dA\*~Xt Net. Several others
have added help along the way.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright (c) 2005, 2006. Ingy dA\*~Xt Net. All rights reserved.
.PP
Copyright (c) 2001, 2002, 2005. Brian Ingerson. All rights reserved.
.PP
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
.PP
See <http://www.perl.com/perl/misc/Artistic.html>