Using callback functions in php classes

Recently learning PHPObject-orientedProgramming, I feel that object-oriented thinking does play a huge role in solving complex problems. I can’t imagine if the StarCraft game was developed How complicated it is without using object-oriented thinking. Object-oriented thinking is indeed a major progress in the history of computer programming methods.

Today I want to call another class method as its callback function in the class method I created. I wanted to write the name of another class method directly in the place of the callback function. However, I kept getting an error saying "the parameter is invalid". Then I thought about whether I should try using the SELF keyword, but I still got this error. I really don’t know what to do. I checked the Chinese manual and couldn’t find a solution. Then I carefully looked at the manual on the PHP official website. This manual has the syntax to solve this problem.

class utils{

 

   public function array_or( $input )

   {

      return array_reduce( $input, array('Utils','sum' ), 0 );

   }

   public function sum( $v, $w )

   {

      return $v += $w;

   }

 

}

$uti = new utils;

$a = array(1,2,3,4,5);

echo $uti->array_or($a);

makes me feel very strange. Why is calling another class method in the form of array? It seems that using the SELF keyword is more appropriate. Hey, I really don’t know what they are doing. What considerations go into designing such a grammar. But I think there must be a reason for the design like this, but I haven't realized this reason yet.

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