PHP7 - class static variable doesn't support variable function

Question

In PHP7.4.3, I'm trying to use class static variable to refer to different class static member functions as below:

1  class ColorT {
2    static $color = "yellow";
3    static function yellow() {
4        echo "yellow"."<br>";
5    }
6    static function green() {
7        echo "green"."<br>";
8    }
9  }

10 ColorT::$color();  //ColorT::yellow() function is expected to be called

11 $global_color = "yellow";
12 ColorT::$global_color();  //ColorT::yellow() function is expected to be called

Both line 10 and line 12, I expect ColorT::yellow() to be invoked.
Line 12 works as expected.
But in line 10, it print error :

PHP Fatal error: Uncaught Error: Function name must be a string

Doesn't php support class static variable referring to class static member functions?
If it's supported, then how to fix the error mentioned in line 10?

Would ColorT::{ColorT::$color}(); help? I'm not sure if your priority is to only use the classname once, or just to be able to call the method dynamically in one line. That should work as far back as PHP 5.4. See 3v4l.org/kbBVq — iainn
– iainn, Commented Jan 15, 2021 at 16:53
@iainn I just want to call the method dynamically in one line and your solution works! Thanks. — macyou
– macyou, Commented Jan 15, 2021 at 18:31

Syscall · Accepted Answer · 2021-01-15 16:47:15Z

3

In line 10, ColorT::$color is "yellow". So ColorT::$color() would call yellow(), not ColorT::yellow().

You could use the callbable ['ColorT', ColorT::$color] for this, to call ColorT::yellow(), dynamically.

Example :

class ColorT {
  static $color = "yellow";
  static function yellow() {
      echo "yellow"."<br>";
  }
  static function green() {
      echo "green"."<br>";
  }
}

$method = ['ColorT', ColorT::$color];
$method();

Output :

yellow<br>

Another way is to create a method in ColorT :

static public function callFunc() 
{
    [__class__, self::$color]();
}

and use

ColorT::callFunc(); // "yellow<br>"

You can also check using is_callable()

edited Jan 15, 2021 at 16:47

answered Jan 15, 2021 at 16:41

Syscall

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