What are PHP traits and when should you use them?

Question

What are PHP traits and when should you use them?

Answer

A trait is a group of methods intended for reuse in multiple classes. Traits help avoid code duplication when classes don't share a natural inheritance hierarchy.

trait Timestampable
{
    private ?DateTime $createdAt = null;
    private ?DateTime $updatedAt = null;

    public function setCreatedAt(): void
    {
        $this->createdAt = new DateTime();
    }

    public function setUpdatedAt(): void
    {
        $this->updatedAt = new DateTime();
    }

    public function getCreatedAt(): ?DateTime { return $this->createdAt; }
    public function getUpdatedAt(): ?DateTime { return $this->updatedAt; }
}

trait SoftDeletable
{
    private ?DateTime $deletedAt = null;

    public function softDelete(): void { $this->deletedAt = new DateTime(); }
    public function isDeleted(): bool  { return $this->deletedAt !== null; }
}

class Article
{
    use Timestampable, SoftDeletable; // use multiple traits
}

class Product
{
    use Timestampable; // reuse just what you need
}

When to Use Traits

• Shared behaviour across unrelated classes (logging, timestamps, soft delete)
• When multiple inheritance would otherwise be needed
• When extracting to a base class would create an unnatural hierarchy

When NOT to Use Traits

• Don't use traits to share business logic — prefer services or composition
• Avoid traits with state that conflicts between classes