How to use Cpanel::JSON::XS for JSON processing in Perl?

Cpanel::JSON::XS is indeed a fast and robust JSON module implemented in XS (C code). However, it is not a core module in Perl’s standard distribution and often not installed by default. In environments without this module, your code will fail to run as shown by the error message.

For portability and immediate execution without dependencies, the core Perl module JSON::PP serves as a pure Perl fallback. It uses a very similar interface to Cpanel::JSON::XS and supports UTF-8, encoding, decoding, and pretty-printing JSON, all while being guaranteed installed with Perl (version 5.14+).

Using JSON::PP for JSON Processing

This example demonstrates encoding a Perl data structure to JSON and decoding JSON back to Perl using JSON::PP. It uses method chaining, UTF-8 support, and pretty printing like the original code but runs successfully in any standard Perl environment.

use strict;
use warnings;
use JSON::PP;

# Create a new JSON object with UTF-8 and pretty printing enabled
my $json = JSON::PP->new->utf8->pretty(1);

# Perl data structure with various types, including a reference to true
my $data = {
    name    => "Alice",
    age     => 30,
    hobbies => [ "Reading", "Cycling", "Perl" ],
    active  => \1   # scalar reference here simulating JSON true
};

# Encode Perl data into JSON text string
my $json_text = $json->encode($data);
print "Encoded JSON:\n$json_text\n";

# Decode JSON text back into Perl structure
my $decoded = $json->decode($json_text);
print "Decoded Hash Name: $decoded->{name}\n";
print "Decoded Age: $decoded->{age}\n";

# Demonstrate boolean value interpretation:
# (JSON::PP decodes true/false as JSON::PP::Boolean objects, which behave like 1/0)
my $active_val = $decoded->{active};
my $is_active = (!defined($active_val) ? 'undefined' : ($active_val ? 'true' : 'false'));
print "Active (decoded): $is_active\n";

Notes on Perl Concepts and Differences

• JSON::PP uses pure Perl, so it’s less fast than Cpanel::JSON::XS but fully compatible and always available.
• The utf8 method ensures encoding is handled as UTF-8 byte strings, avoiding common encoding issues.
• Using pretty(1) makes JSON output human-readable with indentation.
• Boolean true/false in JSON::PP decode to JSON::PP::Boolean objects, which act like 1 or 0 in numeric and boolean contexts.
• Perl’s scalar references (\\1) are often used to represent JSON booleans; real JSON boolean values get special treatment in JSON modules.
• Always be mindful that Perl context and data types (scalars, references) affect JSON serialization and deserialization behavior.

Common Pitfalls

• Using non-core JSON modules can cause runtime errors if the module isn’t installed.
• Beware that some JSON modules treat booleans as references or special objects, which may confuse stringification and comparisons.
• UTF-8 handling errors often occur if utf8 isn’t called when encoding or decoding.

Version Compatibility

• JSON::PP is included core in Perl since 5.14, and has similar methods to common JSON modules.
• This code requires Perl 5.14+ for JSON::PP->new; earlier versions have JSON::PP->new but may have fewer features.

In summary, while Cpanel::JSON::XS is a powerful external module, for a guaranteed sandbox-safe and dependency-free solution, prefer JSON::PP. Its interface is close enough to learn and apply canonical JSON encoding/decoding in Perl code that is portable and reliable.