class - Method name must be a string, error in PHP -

here code,

class tasks {     public $parent;      public function __construct($parent) {         $this->parent = $parent;     }      public function get_task($parent) {         return mysqli_query($db, "select task, status, created_at tasks parent '$parent' , user='$user_id'");     } }  $project = new tasks("null");  print "<div class='project'>" . $project->$get_task() . "</div>"; 

i expect should pass "null" mysql_query , return result(s). error,

fatal error: method name must string 

update: fix didn't make instances of class. instead passed value wanted function tasks::get_task(value-here).

replace

print "<div class='project'>" . $project->$get_task() . "</div>"; 

with

print "<div class='project'>" . $project->get_task() . "</div>"; 

(remove $ sign).