PHP strict standards error text added to results on the page - php

Question

This is the error message generated:
Strict Standards: call_user_func_array() expects parameter 1 to be a
valid callback, non-static method
ModCareercoachoccupationsHelper::getRelated() should not be called
statically in
/customers/f/0/0/studiomitchell.agency/httpd.www/libraries/joomla/cache/controller/callback.php
on line 152
<?php
/**
* #package Joomla.Platform
* #subpackage Cache
*
* #copyright Copyright (C) 2005 - 2016 Open Source Matters, Inc. All rights reserved.
* #license GNU General Public License version 2 or later; see LICENSE
*/
defined('JPATH_PLATFORM') or die;
/**
* Joomla! Cache callback type object
*
* #since 11.1
*/
class JCacheControllerCallback extends JCacheController
{
/**
* Executes a cacheable callback if not found in cache else returns cached output and result
*
* Since arguments to this function are read with func_get_args you can pass any number of arguments to this method
* as long as the first argument passed is the callback definition.
*
* The callback definition can be in several forms:
* - Standard PHP Callback array see <https://secure.php.net/callback> [recommended]
* - Function name as a string eg. 'foo' for function foo()
* - Static method name as a string eg. 'MyClass::myMethod' for method myMethod() of class MyClass
*
* #return mixed Result of the callback
*
* #since 11.1
*/
public function call()
{
// Get callback and arguments
$args = func_get_args();
$callback = array_shift($args);
return $this->get($callback, $args);
}
/**
* Executes a cacheable callback if not found in cache else returns cached output and result
*
* #param mixed $callback Callback or string shorthand for a callback
* #param array $args Callback arguments
* #param mixed $id Cache ID
* #param boolean $wrkarounds True to use wrkarounds
* #param array $woptions Workaround options
*
* #return mixed Result of the callback
*
* #since 11.1
*/
public function get($callback, $args = array(), $id = false, $wrkarounds = false, $woptions = array())
{
// Normalize callback
if (is_array($callback))
{
// We have a standard php callback array -- do nothing
}
elseif (strstr($callback, '::'))
{
// This is shorthand for a static method callback classname::methodname
list ($class, $method) = explode('::', $callback);
$callback = array(trim($class), trim($method));
}
elseif (strstr($callback, '->'))
{
/*
* This is a really not so smart way of doing this... we provide this for backward compatability but this
* WILL! disappear in a future version. If you are using this syntax change your code to use the standard
* PHP callback array syntax: <https://secure.php.net/callback>
*
* We have to use some silly global notation to pull it off and this is very unreliable
*/
list ($object_123456789, $method) = explode('->', $callback);
global $$object_123456789;
$callback = array($$object_123456789, $method);
}
if (!$id)
{
// Generate an ID
$id = $this->_makeId($callback, $args);
}
$data = $this->cache->get($id);
$locktest = new stdClass;
$locktest->locked = null;
$locktest->locklooped = null;
if ($data === false)
{
$locktest = $this->cache->lock($id);
if ($locktest->locked == true && $locktest->locklooped == true)
{
$data = $this->cache->get($id);
}
}
$coptions = array();
if ($data !== false)
{
$cached = unserialize(trim($data));
$coptions['mergehead'] = isset($woptions['mergehead']) ? $woptions['mergehead'] : 0;
$output = ($wrkarounds == false) ? $cached['output'] : JCache::getWorkarounds($cached['output'], $coptions);
$result = $cached['result'];
if ($locktest->locked == true)
{
$this->cache->unlock($id);
}
}
else
{
if (!is_array($args))
{
$referenceArgs = !empty($args) ? array(&$args) : array();
}
else
{
$referenceArgs = &$args;
}
if ($locktest->locked == false)
{
$locktest = $this->cache->lock($id);
}
if (isset($woptions['modulemode']) && $woptions['modulemode'] == 1)
{
$document = JFactory::getDocument();
$coptions['modulemode'] = 1;
if (method_exists($document, 'getHeadData'))
{
$coptions['headerbefore'] = $document->getHeadData();
}
}
else
{
$coptions['modulemode'] = 0;
}
ob_start();
ob_implicit_flush(false);
$result = call_user_func_array($callback, $referenceArgs);
$output = ob_get_clean();
$coptions['nopathway'] = isset($woptions['nopathway']) ? $woptions['nopathway'] : 1;
$coptions['nohead'] = isset($woptions['nohead']) ? $woptions['nohead'] : 1;
$coptions['nomodules'] = isset($woptions['nomodules']) ? $woptions['nomodules'] : 1;
$cached = array(
'output' => ($wrkarounds == false) ? $output : JCache::setWorkarounds($output, $coptions),
'result' => $result,
);
// Store the cache data
$this->cache->store(serialize($cached), $id);
if ($locktest->locked == true)
{
$this->cache->unlock($id);
}
}
echo $output;
return $result;
}
/**
* Generate a callback cache ID
*
* #param callback $callback Callback to cache
* #param array $args Arguments to the callback method to cache
*
* #return string MD5 Hash
*
* #since 11.1
*/
protected function _makeId($callback, $args)
{
if (is_array($callback) && is_object($callback[0]))
{
$vars = get_object_vars($callback[0]);
$vars[] = strtolower(get_class($callback[0]));
$callback[0] = $vars;
}
return md5(serialize(array($callback, $args)));
}
}
The site retrieves the data but with this text error also above
the listing.
The callback.php line 152 is as follows:
$result = call_user_func_array($callback, $referenceArgs);
Any help would be great. Thanks

Answer 1

You'll get this error if you define the method non-statically:
class Foo {
public function bar() {
}
}
And then define $callback as either a string:
$callback = 'Foo::bar';
Or an array of strings:
$callback = ['Foo', 'bar'];
And then use it as an argument to call_user_func_array():
call_user_func_array($callback, []);
To avoid this, you can either define the method statically:
public static function bar() { ... }
Or use an instantiated object in your callback:
$callback = [new Foo(), 'bar'];