.. _illegal-function-name:

Illegal function name
---------------------
 
.. meta::
	:description:
		Illegal function name: This error messages appears when there is an attempt to create a closure from a function, whose name is not a valid function.
	:og:image: https://php-errors.readthedocs.io/en/latest/_static/logo.png
	:og:type: article
	:og:title: Illegal function name
	:og:description: This error messages appears when there is an attempt to create a closure from a function, whose name is not a valid function
	:og:url: https://php-errors.readthedocs.io/en/latest/messages/illegal-function-name.html
	:og:locale: en
	:twitter:card: summary_large_image
	:twitter:site: @exakat
	:twitter:title: Illegal function name
	:twitter:description: Illegal function name: This error messages appears when there is an attempt to create a closure from a function, whose name is not a valid function
	:twitter:creator: @exakat
	:twitter:image:src: https://php-errors.readthedocs.io/en/latest/_static/logo.png

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Description
___________
 
This error messages appears when there is an attempt to create a closure from a function, whose name is not a valid function. Numbers, such as float and integers, are not valid function name, and yield this error. Negative numbers, and other types yield a distinct error.

Example
_______

.. code-block:: php

   <?php
   
   const Closure = (0)(...);
   
   var_dump(Closure);
   
   ?>

Solutions
_________

+ Use a string, instead of a number. Check that the string is a valid name for a function or a static method.
+ Ensures that the name is a static expression, and that each element may be resolved at compile time.

Related Error Messages
______________________

+ :ref:`cannot-use-dynamic-function-name-in-constant-expression`

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>`_.