XP records for PHP

Plugin for the XP Compiler which adds a record syntax to the PHP language. Records declare a final class with immutable components for each of its members and appropriate accessors and a constructor, which implements the lang.Value interface.

Example

// Declaration
namespace com\example;

use IteratorAggregate, Traversable;

record Range(int $lo, int $hi) implements IteratorAggregate {
  public function getIterator(): Traversable {
    for ($i= $this->lo; $i <= $this->hi; $i++) {
      yield $i;
    }
  }
}

// Usage
$r= new Range(1, 10);
$r->lo();       // 1
$r->hi();       // 10
$r->toString(); // "com.example.Range(lo: 1, hi: 10)"

foreach ($r as $item) {
  // 1, 2, 3, ... 10
}

Note: The generated toString(), hashCode() and compareTo() methods may be overriden by supplying an implementation in the record body.

Initialization

To verify constructor parameters, add an initialization block as follows:

use lang\IllegalArgumentException;

record Range(int $lo, int $hi) {
  init {
    if ($this->lo > $this->hi) {
      throw new IllegalArgumentException('Lower border may not exceed upper border');
    }
  }
}

This block is called after the members have been initialized from the constructor parameters.

Destructuring

To destructure a record into its members, use the invocation syntax:

// Using the declaration from above:
$r= new Range(1, 10);

// Use https://wiki.php.net/rfc/short_list_syntax (>= PHP 7.1)
[$lo, $hi]= $r();

// Optionally map the members, returns the string "1..10"
$string= $r(fn($lo, $hi) => "{$lo}..{$hi}");

Installation

After installing the XP Compiler into your project, also include this plugin.

$ composer require xp-framework/compiler
# ...

$ composer require xp-lang/xp-records
# ...

No further action is required.

See also

• Kotlin Data Classes
• Java 14 Records
• Java 14 Feature Spotlight: Records
• C# structs
• C# records