.. _cannot-use--"yield-from-"-inside-a-by-reference-generator:

Cannot use \"yield from\" inside a by-reference generator
---------------------------------------------------------
 
.. meta::
	:description:
		Cannot use \"yield from\" inside a by-reference generator: ``yield from`` only emit data by value, not by reference.
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	:og:title: Cannot use \"yield from\" inside a by-reference generator
	:og:description: ``yield from`` only emit data by value, not by reference
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Description
___________
 
``yield from`` only emit data by value, not by reference.

Example
_______

.. code-block:: php

   <?php
   
   function &foo() {
       yield from [1,2,3];
   }
   
   ?>

Solutions
_________

+ Remove the reference sign from the function signature.
+ Refactor the code to use ``yield`` instead.

Changed Behavior
________________

This error may appear following an evolution in behavior, in previous versions. See ` <https://php-changed-behaviors.readthedocs.io/en/latest/behavior/.html>`_.