NAME

    YAML::XS - Perl YAML Serialization using XS and libyaml

SYNOPSIS

        use YAML::XS;
    
        my $yaml = Dump [ 1..4 ];
        my $array = Load $yaml;

DESCRIPTION

    Kirill Simonov's libyaml is arguably the best YAML implementation. The
    C library is written precisely to the YAML 1.1 specification. It was
    originally bound to Python and was later bound to Ruby.

    This module is a Perl XS binding to libyaml which offers Perl the best
    YAML support to date.

    This module exports the functions Dump, Load, DumpFile and LoadFile.
    These functions are intended to work exactly like YAML.pm's
    corresponding functions. Only Load and Dump are exported by default.

CONFIGURATION

      * $YAML::XS::LoadBlessed (since v0.69)

      Default: false.

      The default was changed in version 0.81.

      When set to false, it will not bless data into objects, which can be
      a security problem, when loading YAML from an untrusted source. It
      will silently ignore the tag and just load the data unblessed.

      In PyYAML, this is called SafeLoad.

      If set to true, it will load the following YAML as objects:

          ---
          local: !Foo::Bar [a]
          perl: !!perl/hash:Foo::Bar { a: 1 }
          regex: !!perl/regexp:Foo::Bar pattern

      You can create any kind of object with YAML. The creation itself is
      not the critical part. If the class has a DESTROY method, it will be
      called once the object is deleted. An example with File::Temp
      removing files can be found at
      https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=862373.

      * $YAML::XS::ForbidDuplicateKeys (since 0.84)

      Default: false

      When set to true, Load will die when encountering a duplicate key in
      a hash, e.g.

          key: value
          key: another value

      This can be useful for bigger YAML documents where it is not that
      obvious, and it is recommended to set it to true. That's also what a
      YAML loader should do by default according to the YAML specification.

      * $YAML::XS::UseCode

      * $YAML::XS::DumpCode

      * $YAML::XS::LoadCode

      If enabled supports deparsing and evaling of code blocks.

      Note that support for loading code was added in version 0.75,
      although $LoadCode was documented already in earlier versions.

      * $YAML::XS::QuoteNumericStrings

      When true (the default) strings that look like numbers but have not
      been numified will be quoted when dumping.

      This ensures leading that things like leading zeros and other
      formatting are preserved.

      * $YAML::XS::Boolean (since v0.67)

      Default: undef

      Since YAML::XS 0.89: When used with perl 5.36 or later, builtin
      booleans will work out of the box. They will be created by Load and
      recognized by Dump automatically (since YAML::XS 0.89).

          say Dump({ truth => builtin::true });
          # truth: true

      Since YAML::XS v0.902: loaded booleans are not set to readonly
      anymore.

      For older perl versions you can use the following configuration to
      serialize data as YAML booleans:

      When set to "JSON::PP" or "boolean", the plain (unquoted) strings
      true and false will be loaded as JSON::PP::Boolean or boolean.pm
      objects. Those objects will be dumped again as plain "true" or
      "false".

      It will try to load [JSON::PP] or [boolean] and die if it can't be
      loaded.

      With that it's possible to add new "real" booleans to a data
      structure:

          local $YAML::XS::Boolean = "JSON::PP"; # or "boolean"
          my $data = Load("booltrue: true");
          $data->{boolfalse} = JSON::PP::false;
          my $yaml = Dump($data);
          # boolfalse: false
          # booltrue: true

      It also lets booleans survive when loading YAML via YAML::XS and
      encode it in JSON via one of the various JSON encoders, which mostly
      support JSON::PP booleans.

      Please note that JSON::PP::Boolean and boolean.pm behave a bit
      differently. Ideally you should only use them in boolean context.

      If not set, booleans are loaded as special perl variables PL_sv_yes
      and PL_sv_no, which have the disadvantage that they are readonly, and
      you can't add those to an existing data structure with pure perl.

      If you simply need to load "perl booleans" that are true or false in
      boolean context, you will be fine with the default setting.

      * $YAML::XS::Indent (since v0.76)

      Default is 2.

      Sets the number of spaces for indentation for Dump.

USING YAML::XS WITH UNICODE

    Handling unicode properly in Perl can be a pain. YAML::XS only deals
    with streams of utf8 octets. Just remember this:

        $perl = Load($utf8_octets);
        $utf8_octets = Dump($perl);

    There are many, many places where things can go wrong with unicode. If
    you are having problems, use Devel::Peek on all the possible data
    points.

LIBYAML

    You can find out (since v.079) which libyaml version this module was
    built with:

        my $libyaml_version = YAML::XS::LibYAML::libyaml_version();

SEE ALSO

      * YAML.pm

      * YAML::Syck

      * YAML::Tiny

      * YAML::PP

      * YAML::PP::LibYAML

AUTHOR

    Ingy döt Net ingy@ingy.net <mailto:ingy@ingy.net>

COPYRIGHT AND LICENSE

    Copyright 2007-2024 - Ingy döt Net

    This program is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.

    See http://www.perl.com/perl/misc/Artistic.html

