The Traversable interface

Introduction

Interface to detect if a class is traversable using foreach.

Abstract base interface that cannot be implemented alone. Instead, it must be implemented by either IteratorAggregate or Iterator.

Interface synopsis

This interface has no methods; its only purpose is to be the base interface for all traversable classes.

Changelog

Notes

Note: Internal (built-in) classes that implement this interface can be used in a foreach construct and do not need to implement IteratorAggregate or Iterator.

Note: Prior to PHP 8.0.0, this internal engine interface couldn't be directly implemented in PHP scripts — not even by abstract classes. Either IteratorAggregate or Iterator must be used instead.