Traits in PHP

Sharing behavior across classes without inheritance.

<?php
// a trait holds methods; use mixes them into any class
trait Greets {
    public function greet(): string {
        return "hi, I am " . $this->name();
    }
}

class Robot {
    use Greets;

    public function __construct(private int $id) {}

    public function name(): string {
        return "unit-" . $this->id;
    }
}

echo (new Robot(7))->greet(), "\n";

How it works

1. A trait defines methods with no class of their own.
2. use Greets; copies them into Robot as instance methods.
3. The trait calls $this->name(), which the host class provides.

Keywords and builtins used here

• Robot
• class
• echo
• function
• greet
• name
• new
• private
• public
• return
• trait
• use

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Step 3 of 3 in Classes, step 18 of 27 in Language basics.

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Traits in other languages

• Rust
• Scala