Введение
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.
Замечание:
Internal (built-in) classes that implement this interface can be used in
a foreach construct and do not need to implement
IteratorAggregate or
Iterator.
Замечание:
This is an internal engine interface which cannot be implemented in PHP
scripts. Either IteratorAggregate or
Iterator must be used instead.