(PHP 5, PHP 7, PHP 8)
Interface para detectar se uma classe é percorrível utilizando o foreach.
Interface básica abstrata que não pode ser implementada sozinha. Ao invés, deve ser implementada as interfaces IteratorAggregate ou Iterator.
Esta interface não possui métodos, seu único propósito é de servir como interface base para todas as classes percorríveis.
| Versão | Descrição |
|---|---|
| 7.4.0 | A interface Traversable agora pode ser implementada em classes abstratas. Classes estendidas precisam implementar Iterator ou IteratorAggregate. |
Nota:
Classes internas (built-in) que implementam essa interface podem ser utilizadas em um construtor de linguagem
foreache não precisam implementar as interfaces IteratorAggregate ou Iterator.
Nota:
Anteriormente ao PHP 7.4.0, esta funcionalidade interna não podia ser implementada em scripts PHP. Ou IteratorAggregate ou Iterator precisavam ser utilizados.
While you cannot implement this interface, you can use it in your checks to determine if something is usable in for each. Here is what I use if I'm expecting something that must be iterable via foreach.
<?php
if( !is_array( $items ) && !$items instanceof Traversable )
//Throw exception here
?>NOTE: While objects and arrays can be traversed by foreach, they do NOT implement "Traversable", so you CANNOT check for foreach compatibility using an instanceof check.
Example:
$myarray = array('one', 'two', 'three');
$myobj = (object)$myarray;
if ( !($myarray instanceof \Traversable) ) {
print "myarray is NOT Traversable";
}
if ( !($myobj instanceof \Traversable) ) {
print "myobj is NOT Traversable";
}
foreach ($myarray as $value) {
print $value;
}
foreach ($myobj as $value) {
print $value;
}
Output:
myarray is NOT Traversable
myobj is NOT Traversable
one
two
three
one
two
threeThe PHP7 iterable pseudo type will match both Traversable and array. Great for return type-hinting so that you do not have to expose your Domain to Infrastructure code, e.g. instead of a Repository returning a Cursor, it can return hint 'iterable':
<?php
UserRepository::findUsers(): iterable
?>
Link: http://php.net/manual/en/migration71.new-features.php#migration71.new-features.iterable-pseudo-type
Also, instead of:
<?php
if( !is_array( $items ) && !$items instanceof Traversable )
//Throw exception here
?>
You can now do with the is_iterable() method:
<?php
if ( !is_iterable( $items ))
//Throw exception here
?>
Link: http://php.net/manual/en/function.is-iterable.phpNote that all objects can be iterated over with foreach anyway and it'll go over each property. This just describes whether or not the class implements an iterator, i.e. has custom behaviour.