CODEWITHSUNDEEP
phpoopdynamicstaticproperties
treznik
treznik

Reputation: 8124

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

I have this:

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:

Upvotes: 57

Views: 43338

Answers (11)

Garlou
Garlou

Reputation: 9

You can use ReflectionClass:

class foo
{
    private static $bar = "something";
}

$class = "foo";
$reflector = new ReflectionClass($class);
$static_vars = $reflector->getStaticProperties();
var_dump($static_vars["bar"]);

Upvotes: 0

Arul Kumaran
Arul Kumaran

Reputation: 993

Getting and setting both static and non static properties without using Reflection

Using Reflection works but it is costly

Here is what I use for this purpose,

It works for PHP 5 >= 5.1.0 because I'm using property_exist

function getObjectProperty($object, $property)
{
    if (property_exists(get_class($object), $property)) {
        return array_key_exists($property, get_object_vars($object))
            ? $object->{$property}
            : $object::$$property;
    }
}

function setObjectProperty($object, $property, $value)
{
    if (property_exists(get_class($object), $property)) {
        array_key_exists($property, get_object_vars($object))
            ? $object->{$property} = $value
            : $object::$$property = $value;
    }
}

Upvotes: 0

Marco Demaio
Marco Demaio

Reputation: 34407

Even if for you said eval is out of the question, prior PHP 5.3 the easiest solution is still by using eval:

eval("\$propertyval = $classname::\$propertyname;");
echo $propertyval;

Upvotes: 0

firzen
firzen

Reputation: 1

get_class_vars is not same as get_object_vars.

I think get_clas_vars should return the original property values.

Upvotes: 0

frodosghost
frodosghost

Reputation: 520

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

Upvotes: 14

Bahadır
Bahadır

Reputation: 171

I think this is the simplest:

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

Upvotes: 17

mbirth
mbirth

Reputation: 11

One thing I noticed is that you can't set variables which are protected in static classes as the eval() command runs in a scope outside the class. The only thing to get around this would be to implement a static method inside the/every class which runs the eval(). This method could be protected as the call_user_func() [to call the setter method] also runs from inside the class.

Upvotes: 1

Andrew Moore
Andrew Moore

Reputation: 95344

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.

Upvotes: 86

Alex Weinstein
Alex Weinstein

Reputation: 9891

Potentially relevant: discussion on late static binding in PHP - When would you need to use late static binding?.

Upvotes: 0

nilamo
nilamo

Reputation: 1942

'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'.

Upvotes: 1

Steven Surowiec
Steven Surowiec

Reputation: 10220

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.

Upvotes: 1

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