.. _only-arrays-and-traversables-can-be-unpacked:

Only arrays and Traversables can be unpacked
--------------------------------------------
 
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		Only arrays and Traversables can be unpacked: The triple dot ``.
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Description
___________
 
The triple dot ``...`` operator works on arrays and traversables, such as ``generator``, ``iterators``... It cannot work on other data structures.

Also, ``...`` has a lower priority than the null-coalesce operator ``??``, so it applies to both branch of the operator.

Example
_______

.. code-block:: php

   <?php
   
   $a = null;
   foo(...$a);
   
   foo(...$a ?? range(1,2));
   // displays 1, 2
   
   function foo() {
       print_r(func_get_args());
   }
   
   ?>

Solutions
_________

+ Check that the value is an array or a traverable before using the ``...`` operator.
+ Use the ``??`` operator to give a value to ``null`` before the ``...`` operator.
+ Use the ``?:`` operator to give a value to empty data before the ``...`` operator.

Related Error Messages
______________________

+ :ref:`only-arrays-can-be-unpacked-in-constant-expression`