Question

I’m wrapping my inferior mind around classes. It is struggling with it by looking at other peoples code and finding it hard to see how it relates to my own code. I am hoping you can help me see how it works by turning 2 simple functions I have into classes so that I can see a relatable example.

A simple couple of functions:

function make_url_friendly($string) {

  $remove = array(',',' ','?','=','&','-','|');
  $replace = array('_','_','_','_','','_','');

  $string = strtolower(str_replace($remove,$replace,$string));  
  return $string;

}

function save_page($url) {

 $sql = 'INSERT INTO pages 
        SET url="' . mysql_real_escape_string(make_url_friendly($url)) . '" ';
 mysql_query($sql);

}


save_page('/questions/ask');

What might be the oop equivalent to functions like this?

Answer 1

class URLHandler{

   // Class variables
   $url = "";

   // Constructors
   public URLHandler($newurl) {  // Old Style
      $this->__construct($newurl);
   }

   public __construct($newurl) {  // New Style
      $this->setUrl($newurl);
   }

   private function make_url_friendly($string) {
      $remove = array(',',' ','?','=');
      $string = strtolower(str_replace($remove,"_",$string));
      return $string;
   }

   public function save_page() {
      $sql = 'INSERT INTO pages 
        SET url="' . mysql_real_escape_string($this->url) . '" ';
      mysql_query($sql);

   }

   public function getUrl(){
      return $this->url;
   }
   public function setUrl($newurl){
      $this->url = $this->make_url_friendly($newurl);
   }
};


//save_page('/questions/ask');
$somevar = new URLHandler("/questions/ask");
$somevar->save_page();

$somevar->setUrl("/answers/answer");
$somevar->save_page();

Edit:

As Shef pointed out in the comments, you really want to group items of similar function into their own class. For example, all your function s which do something to the DB would have a class different than your functions which handle form error checking.

Therefore in your example make_url_friendly would be in a different class from save_page