PHP Detection Interface Traversable Usage example

Source: Internet
Author: User
Tags throw exception
This article mainly introduces the PHP detection interface traversable usage, combined with the case analysis of the Traversable interface detection traversal function related operation skills, the need for friends can refer to, hope to help everyone.

Traversable is used to detect whether a class can traverse using foreach, an internal engine interface that cannot be implemented in a PHP script, and we use the iterator interface or the Iteratoraggregate interface to implement traversal in real-world programming.

Interface Summary:

traversable {}

One of the important uses of traversable is to determine if a class can traverse, and here is the official example:

<?php  if (!is_array ($items) &&! $items instanceof traversable)    //throw exception here?>

It is important to note that arrays and objects can be traversed through foreach, but they do not implement the Traversable interface, so this is not an example of traversable:

<?php$array=[1,2,3]; $obj = (object) $array; Var_dump ($array instanceof \traversable); Var_dump ($obj instanceof \ traversable);? >

The above code output:

Boolean Falseboolean False

Additional notes:

Class does not implement the iterator interface or the Iteratoraggregate interface, executing a foreach traversal outputs all of the visible properties that it can access

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