Struct Embedding in PHP

PHP supports object-oriented programming, which we can use to demonstrate a concept similar to struct embedding. We’ll use inheritance to showcase a similar behavior.

<?php

class Base {
    public $num;

    public function __construct($num) {
        $this->num = $num;
    }

    public function describe() {
        return sprintf("base with num=%d", $this->num);
    }
}

// Container inherits from Base
class Container extends Base {
    public $str;

    public function __construct($num, $str) {
        parent::__construct($num);
        $this->str = $str;
    }
}

// Main execution
$co = new Container(1, "some name");

// We can access the base's properties directly on $co
printf("co={num: %d, str: %s}\n", $co->num, $co->str);

// We can also access the base's properties using parent::
echo "also num: " . $co->num . "\n";

// Since Container extends Base, the methods of Base are also available to Container
echo "describe: " . $co->describe() . "\n";

// PHP doesn't have interfaces in the same way as Go, but we can use abstract classes
abstract class Describer {
    abstract public function describe();
}

// We can implement the abstract class to achieve a similar effect
class DescribableContainer extends Container {
    public function describe() {
        return parent::describe();
    }
}

$d = new DescribableContainer(1, "some name");
echo "describer: " . $d->describe() . "\n";

To run this PHP script, save it as class-inheritance.php and execute it using the PHP CLI:

$ php class-inheritance.php
co={num: 1, str: some name}
also num: 1
describe: base with num=1
describer: base with num=1

In this PHP example, we’ve used class inheritance to demonstrate a concept similar to struct embedding in Go. The Container class extends the Base class, which allows it to inherit properties and methods from Base. This is analogous to embedding in Go, although the syntax and some behaviors differ.

We’ve also shown how to implement an abstract class (Describer) to achieve a similar effect to Go’s interface implementation through embedding. In PHP, a class that extends an abstract class must implement all of its abstract methods.

While PHP doesn’t have a direct equivalent to Go’s struct embedding, inheritance and abstract classes provide ways to achieve similar compositional patterns and method implementations.

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Struct Embedding in PHP