Packed Classes

A packed class is a flat record with compile-time field offsets. Designed for hot-path data that needs predictable layouts and zero hash overhead.

Declaration

<?php
packed class Enemy {
    int $x;
    int $y;
    int $hp;
    int $state;
}

Constraints

• Fields must be int, float, bool, ptr, or another packed class
• No union or nullable types
• No strings, arrays, objects, or mixed values
• No methods, constructors, inheritance, traits, or interfaces
• Only public visibility (optional and redundant)
• No default values
• Layout is sequential: field 0 at offset 0, field 1 at offset 8, etc.

Usage with buffers

<?php
packed class Vertex {
    float $x;
    float $y;
    float $u;
    float $v;
    int $color;
}

buffer<Vertex> $verts = buffer_new<Vertex>(1024);
$verts[0]->x = 10.0;
echo $verts[0]->x;  // 10

Best practices

• Use packed classes for structured hot-path data instead of associative arrays
• Prefer SoA (parallel buffers) for large datasets where you iterate one field at a time
• Use AoS (buffer of packed class) when you always access all fields together