JSON::MaybeXS(3pm) User Contributed Perl Documentation JSON::MaybeXS(3pm)
NAME
JSON::MaybeXS - Use Cpanel::JSON::XS with a fallback to JSON::XS and
JSON::PP
SYNOPSIS
use JSON::MaybeXS;
my $data_structure = decode_json($json_input);
my $json_output = encode_json($data_structure);
my $json = JSON()->new;
my $json_with_args = JSON::MaybeXS->new(utf8 => 1); # or { utf8 => 1 }
DESCRIPTION
This module first checks to see if either Cpanel::JSON::XS or JSON::XS
(at at least version 3.0) is already loaded, in which case it uses that
module. Otherwise it tries to load Cpanel::JSON::XS, then JSON::XS,
then JSON::PP in order, and either uses the first module it finds or
throws an error.
It then exports the "encode_json" and "decode_json" functions from the
loaded module, along with a "JSON" constant that returns the class name
for calling "new" on.
If you're writing fresh code rather than replacing JSON.pm usage, you
might want to pass options as constructor args rather than calling
mutators, so we provide our own "new" method that supports that.
EXPORTS
"encode_json", "decode_json" and "JSON" are exported by default;
"is_bool" is exported on request.
To import only some symbols, specify them on the "use" line:
use JSON::MaybeXS qw(encode_json decode_json is_bool); # functions only
use JSON::MaybeXS qw(JSON); # JSON constant only
To import all available sensible symbols ("encode_json", "decode_json",
and "is_bool"), use ":all":
use JSON::MaybeXS ':all';
To import all symbols including those needed by legacy apps that use
JSON::PP:
use JSON::MaybeXS ':legacy';
This imports the "to_json" and "from_json" symbols as well as
everything in ":all". NOTE: This is to support legacy code that makes
extensive use of "to_json" and "from_json" which you are not yet in a
position to refactor. DO NOT use this import tag in new code, in order
to avoid the crawling horrors of getting UTF-8 support subtly wrong.
See the documentation for JSON for further details.
encode_json
This is the "encode_json" function provided by the selected
implementation module, and takes a perl data structure which is
serialised to JSON text.
my $json_text = encode_json($data_structure);
decode_json
This is the "decode_json" function provided by the selected
implementation module, and takes a string of JSON text to deserialise
to a perl data structure.
my $data_structure = decode_json($json_text);
to_json, from_json
See JSON for details. These are included to support legacy code only.
JSON
The "JSON" constant returns the selected implementation module's name
for use as a class name - so:
my $json_obj = JSON()->new; # returns a Cpanel::JSON::XS or JSON::PP object
and that object can then be used normally:
my $data_structure = $json_obj->decode($json_text); # etc.
The use of parentheses here is optional, and only used as a hint to the
reader that this use of "JSON" is a subroutine call, not a class name.
is_bool
$is_boolean = is_bool($scalar)
Returns true if the passed scalar represents either "true" or "false",
two constants that act like 1 and 0, respectively and are used to
represent JSON "true" and "false" values in Perl.
Since this is a bare sub in the various backend classes, it cannot be
called as a class method like the other interfaces; it must be called
as a function, with no invocant. It supports the representation used
in all JSON backends.
Available since version 1.002004.
CONSTRUCTOR
new
With JSON::PP, JSON::XS and Cpanel::JSON::XS you are required to call
mutators to set options, such as:
my $json = $class->new->utf8(1)->pretty(1);
Since this is a trifle irritating and noticeably un-perlish, we also
offer:
my $json = JSON::MaybeXS->new(utf8 => 1, pretty => 1);
which works equivalently to the above (and in the usual tradition will
accept a hashref instead of a hash, should you so desire).
The resulting object is blessed into the underlying backend, which
offers (at least) the methods "encode" and "decode".
BOOLEANS
To include JSON-aware booleans ("true", "false") in your data, just do:
use JSON::MaybeXS;
my $true = JSON()->true;
my $false = JSON()->false;
The booleans are also available as subs or methods on JSON::MaybeXS.
use JSON::MaybeXS ();
my $true = JSON::MaybeXS::true;
my $true = JSON::MaybeXS->true;
my $false = JSON::MaybeXS::false;
my $false = JSON::MaybeXS->false;
CONVERTING FROM JSON::Any
JSON::Any used to be the favoured compatibility layer above the various
JSON backends, but over time has grown a lot of extra code to deal with
legacy backends (e.g. JSON::Syck) that are no longer needed. This is a
rough guide of translating such code:
Change code from:
use JSON::Any;
my $json = JSON::Any->new->objToJson($data); # or to_json($data), or Dump($data)
to:
use JSON::MaybeXS;
my $json = encode_json($data);
Change code from:
use JSON::Any;
my $data = JSON::Any->new->jsonToObj($json); # or from_json($json), or Load($json)
to:
use JSON::MaybeXS;
my $json = decode_json($data);
CAVEATS
The "new()" method in this module is technically a factory, not a
constructor, because the objects it returns will NOT be blessed into
the "JSON::MaybeXS" class.
If you are using an object returned by this module as a Moo(se)
attribute, this type constraint code:
is 'json' => ( isa => 'JSON::MaybeXS' );
will NOT do what you expect. Instead, either rely on the "JSON" class
constant described above, as so:
is 'json' => ( isa => JSON::MaybeXS::JSON() );
Alternatively, you can use duck typing:
use Moose::Util::TypeConstraints 'duck_type';
is 'json' => ( isa => Object , duck_type([qw/ encode decode /]));
INSTALLATION
At installation time, Makefile.PL will attempt to determine if you have
a working compiler available, and therefore whether you are able to run
XS code. If so, Cpanel::JSON::XS will be added to the prerequisite
list, unless JSON::XS is already installed at a high enough version.
JSON::XS may also be upgraded to fix any incompatibility issues.
Because running XS code is not mandatory and JSON::PP (which is in perl
core) is used as a fallback backend, this module is safe to be used in
a suite of code that is fatpacked or installed into a restricted-
resource environment.
You can also prevent any XS dependencies from being installed by
setting "PUREPERL_ONLY=1" in Makefile.PL options (or in the
"PERL_MM_OPT" environment variable), or using the "--pp" or
"--pureperl" flags with the cpanminus client.
AUTHOR
mst - Matt S. Trout (cpan:MSTROUT) <mst@shadowcat.co.uk>
CONTRIBUTORS
• Clinton Gormley <drtech@cpan.org>
• Karen Etheridge <ether@cpan.org>
• Kieren Diment <diment@gmail.com>
COPYRIGHT
Copyright (c) 2013 the "JSON::MaybeXS" "AUTHOR" and "CONTRIBUTORS" as
listed above.
LICENSE
This library is free software and may be distributed under the same
terms as perl itself.
perl v5.34.0 2022-09-21 JSON::MaybeXS(3pm)
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