PHP Access static property from dynamic class name

Question

I'm trying to access a static property from a dynamic class.

class A {
    public static $myvar = 'A Class';
}

class B {
    public static $myvar = 'B Class';
}

Somewhere else:

public function getMyVar($classname) {
    return ??????::$myvar; // help here!!
}

$a = getMyVar('A'); // I want 'A Class'
$b = getMyVar('B'); // I want 'B Class'

My Question: how do I access $myvar depending on what gets sent in to getMyVar() ?

EDIT: The class can be one of many (say 50-100 possible) so I'm looking for a short method

Is my only option having to make $myvar not-static??

NEW2WEB · Accepted Answer · 2014-07-22 17:29:21Z

2

I solved it.

The static variable can be accessed by:

public function getMyVar($classname) {
    return $classname::$myvar;
}

That was a lot easier than anticipated! :)

answered Jul 22, 2014 at 17:29

NEW2WEB

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lpg · Accepted Answer · 2014-07-22 17:24:40Z

0

Something like this?

    function getMyVar($classname) {
            switch($classname) {
                    case 'A': return A::$myvar;
                    case 'B': return B::$myvar;
            }
    }

EDIT: If you have so many classes, maybe you can try with this?

    function getMyVar($classname) {
            eval('$var='.$classname.'::$myvar;');
            return $var;
    }

edited Jul 22, 2014 at 17:24

answered Jul 22, 2014 at 17:17

lpg

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2 Comments

NEW2WEB Over a year ago

Fair enough, unfortunately I have many possible classes (50+).

sstur Over a year ago

eval is a really bad thing to use

Trick · Accepted Answer · 2014-07-23 00:13:13Z

This is similar to a previous answer, but performs some sanity checking to ensure that what you're trying to access exists, and is a valid object reference.

Save to demo.php, chmod +x demo.php && ./demo.php.

    #!/usr/bin/php
    <?php

    class A {
      public static $myvar = 'A Class';
      public static $test1 = 'TEST_VALUE_1';
      public static $test2 = 'TEST_VALUE_2';
    }

    class B {
      public static $myvar = 'B Class';
    }


    /**
     * Gets a static variable from the specified class. 
     * Returns FALSE if the property or class does not exist, otherwise returns the value of the property.
     * @param string|object $className Can be either the class name (string) or an object (i.e., "A" or A).
     * @param string $varName
     * @return mixed|boolean 
     */
    function getClassStaticVar($className, $varName) {
      if ((is_string($className) && class_exists($className) ) || is_object($className))
        if (property_exists($className, $varName)) {
          return $className::$$varName;
        }
      return FALSE;  //if your property value is potentially FALSE, you might want to return another value here, like NULL.
    }

    function getMyVar($className) {
      if (is_string($className) || is_object($className)) //is className a string or object reference? 
        return getClassStaticVar($className, 'myvar'); // --or--  return $className::$myvar;
      return FALSE;
    }


    $a = getMyVar('A'); // I want 'A Class'
    $b = getMyVar('B'); // I want 'B Class'

    //in real code, you'd check if $a/$b === FALSE here. (see comment in getClassStaticVar() above)
    echo ($a===FALSE ? 'Property/Class not found' : $a) . PHP_EOL;
    echo $b . PHP_EOL;
    echo getClassStaticVar("A", 'test1') . PHP_EOL;
    echo getClassStaticVar(new A(), 'test2') . PHP_EOL;

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