Voting

The Note You're Voting On

sebastien at info-conseil dot fr ¶
17 years ago
Here is a small workaround I made for the static inheritance issue. It's not perfect, but it works.

<?php

// BaseClass class will be extended by any class needing static inheritance workaroud
class BaseClass {
    // Temporarily stores class name for Entry::getStatic() and Entry::setNextStatic()
    protected static $nextStatic = false;
    
    // Returns the real name of the class calling the method, not the one in which it was declared.
    protected static function getStatic() {
        // If already stored
        if (self::$nextStatic) {
            // Clean and return
            $class = self::$nextStatic;
            self::$nextStatic = false;
            return $class;
        }
        
        // Init
        $backTrace = debug_backtrace();
        $class = false;
        
        // Walk through
        for ($i=0; $i<count($backTrace); $i++) {
            // If a class is defined
            if (isset($backTrace[$i]['class'])) {
                // Check if it is not a basic class
                if (!in_array($backTrace[$i]['class'], array('BaseClass', 'GenericClass'))) {
                    return $backTrace[$i]['class'];
                } else {
                    $class = $backTrace[$i]['class'];
                }
            } else {
                // Returns last known class
                return $class;
            }
        }
        
        // Default
        return $class;
    }
    
    // If a static method is called within global env, the previous method won't work, so we need to tell BaseClass which
    public static function setNextStatic($class) {
        // Save value
        self::$nextStatic = $class;
    }
}

// Generic class declaring various static methods
class GenericClass extends BaseClass {
    public static $name = 'Generic';
    
    public function getName() {
        $static = get_class_vars(get_class($this));
        return $static['name'];
    }
    
    public static function basicClassName() {
        return self::$name;
    }
    
    public static function staticClassName() {
        // Get real name
        $staticName = self::getStatic();
        
        // Return final class name
        $static = get_class_vars($staticName);
        return $static['name'];
    }
}

// Final class
class SomeClass extends GenericClass {
    public static $name = 'Some';
    
    public static function returnClassNameWith($string) {
        return $string.' : '.self::staticClassName();
    }
}

// Instance call

// Will print 'Some'
$a = new SomeClass();
echo 'Name of $a : '.$a->getName().'<br />';

// Static calls

// Will print 'Generic'
echo 'Basic call to SomeClass::$name : '.SomeClass::basicClassName().'<br />';

// Will print 'Generic'
echo 'Global call to SomeClass::$name : '.SomeClass::staticClassName().'<br />';

// Will print 'Some'
BaseClass::setNextStatic('SomeClass');
echo 'Global call to SomeClass::$name with pre-set : '.SomeClass::staticClassName().'<br />';

// Will print 'Some'
echo 'Internal call to SomeClass::$name : '.SomeClass::returnClassNameWith('This is a ').'<br />';

?>

There are two issues with this workaround :
- if you call a static method from global env, you need to declare the name of the class BEFORE calling the method, otherwise the workaround won't work (see 3rd and 4th examples). But I assume good programming makes few calls to static methods from global scope, so this shouldn't be long to fix if you use it.
- the workaround fails to access to private or protected static vars, as it uses get_class_vars(). If you find any better solution, let us know.

With Php 5.3.0, upgrading will be easy : just delete the methods from the basic class, and search/replace any call to getStatic() and setNextStatic() by static:: - or one could use a selector on PHP_VERSION value to include either the BaseClass file with workaround or a BaseClass file using static::
<< Back to user notes page