OnceTrait.php

<?php

Trait OnceTrait {
	
  private $once = [];
	
  protected function once($callback, ...$arguments) 
  {		
    $hash = $this->hashOnceMethod(func_get_args());

    if (false === isset($this->once[$hash])) {
      $result = call_user_func_array($callback, $arguments);
      $this->once[$hash] = $result;
    }
    
    return $this->once[$hash];
  }

  protected function hashOnceMethod(array $arguments) 
  {
    return md5(serialize(array_map(function ($value) {
      if (is_array($value)) {
        return $this->hashOnceMethod($value);
      }

      if (is_object($value)) {
        return spl_object_hash($value);
      }

      return $value;

    }, $arguments)));
  }
}