Getting static property from a class with dynamic class name in PHP

I have this:

one string variable which holds the class name ($classname)
one string variable with holds the property name ($propertyname)

I want to get that property from that class, the problem is, the property is static and I don't know how to do that.

If the property weren't static, it would have been:

$classname->$propertyname;

if the property were a method, I could have used call_user_function

call_user_func(array($classname, $propertyname));

But in my case, am I just lost. I am however hoping that it is possible. With the thousands of functions that PHP has, he'd better have something for this as well. Maybe I'm missing something?

Thanks!

Edit:

for those with eval() solutions: thanks, but it is out of the question
for those with get _class _vars() solutions: thanks, but it seems it returns "the default properties of the given class" (php.net), and yes, I would like that value to be changable (even though it does help me in some of the cases)

If you are using PHP 5.3.0 or greater, you can use the following:

$classname::$$propertyname;

~~Unfortunately, if you are using a version lower than 5.3.0, you are stuck using eval() (get_class_vars() will not work if the value is dynamic).~~

$value = eval($classname.'::$'.$propertyname.';');

EDIT: I've just said get_class_vars() wouldn't work if the value is dynamic, but apparently, variable static members are part of "the default properties of a class". You could use the following wrapper:

function get_user_prop($className, $property) {
  if(!class_exists($className)) return null;
  if(!property_exists($className, $property)) return null;

  $vars = get_class_vars($className);
  return $vars[$property];
}

class Foo { static $bar = 'Fizz'; }

echo get_user_prop('Foo', 'bar'); // echoes Fizz
Foo::$bar = 'Buzz';
echo get_user_prop('Foo', 'bar'); // echoes Buzz

Unfortunately, if you want to set the value of the variable, you will still need to use eval(), but with some validation in place, it's not so evil.

function set_user_prop($className, $property,$value) {
  if(!class_exists($className)) return false;
  if(!property_exists($className, $property)) return false;

  /* Since I cannot trust the value of $value
   * I am putting it in single quotes (I don't
   * want its value to be evaled. Now it will
   * just be parsed as a variable reference).
   */
  eval($className.'::$'.$property.'=$value;');
  return true;
}

class Foo { static $bar = 'Fizz'; }

echo get_user_prop('Foo', 'bar'); // echoes Fizz
set_user_prop('Foo', 'bar', 'Buzz');
echo get_user_prop('Foo', 'bar'); // echoes Buzz

set_user_prop() with this validation should be secure. If people start putting random things as $className and $property, it will exit out of the function as it won't be an existing class or property. As of $value, it is never actually parsed as code so whatever they put in there won't affect the script.

I think this is the simplest:

$foo = new ReflectionProperty('myClassName', 'myPropertyName'); 
print $foo->getValue();

To return a variable value that is set by a Static Variable you need to call:

$static_value = constant($classname.'::'.$propertyname);

Check out the documentation :: PHP Constant Documentation

You should be able to do something like:

eval("echo $classname::$propertyname;");

I just did a quick test and got this to work for me. Not sure if there's a better way or not, but I wasn't able to find one.

'eval' looks so close to 'evil', and I hate using it and/or seeing it in code. With a few ideas from other answers, here's a way to avoid it even if your php isn't 5.3 or higher.

Changed to reflect testing based on a comment.

class A {
    static $foo = 'bar';
}

A::$foo = 'baz';
$a = new A;

$class = get_class($a);
$vars = get_class_vars($class);

echo $vars['foo'];

Outputs 'baz'.

Getting static property from a class with dynamic class name in PHP

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