这三个功能如何协同工作？

Question

I am following a php book and am not understanding a few functions.

Specifically,public function DisplayMenu($buttons). I know this creates a table for the menu (home, contact etc and spaces them out). And the parameters here

 public function DisplayButton($width, $name, $url, $active = true)

$width = 100/count($buttons);
    Here is what I am not understanding. Im setting a variable called width to be 100/count ? lets say buttons are 4 so 100/4 25? What is the point of the 25? Also,

$this -> DisplayButton($width, $name, $url, !$this->IsURLCurrentPage($url));

I know what they produce on screen but not understadning the key parts of these fucntiosn. Can some one shed a tiny bit of light.

// variables declared

public $content;
  public $title = 'TLA Consulting Pty Ltd';
  public $keywords = 'TLA Consulting, Three Letter Abbreviation, 
                   some of my best friends are search engines';
  public $buttons = array( 'Home'     => 'home.php', 
                        'Contact'  => 'contact.php', 
                        'Services' => 'services.php', 
                        'Site Map' => 'map.php'
                      );

  // class Page's operations
  public function __set($name, $value)
  {
    $this->$name = $value;
  }

public function DisplayMenu($buttons)
  {

    echo "<table width='100%' bgcolor='red' cellpadding='3' 
                cellspacing='4'\n";
    echo "  <tr>\n";

    $width = 100/count($buttons);

    while (list($name, $url) = each($buttons))
    {

      $this -> DisplayButton($width, $name, $url, !$this->IsURLCurrentPage($url));
    }
    echo "  </tr>\n";
    echo "</table>\n";
  }


  {
    if ($active)
    {
      echo "<td width ='$width%'>
            <a href ='$url'>
            <img src ='s-logo' alt ='$name' border ='0' /></a>
            <a href ='$url'><span class='menu'>$name</span></a></td>";
    }  
    else
    {
      echo "<td width ='$width%'>
            <img src ='side-logo.gif'>
            <span class='test'>$name</span></td>";
    }  
  }





   public function IsURLCurrentPage($url)
  //#determines weather a url for the button points to the current page.
  // #the server[php_self,$url] returns a number if the string in $url is inside the superglobal variable $_server[pph]
  {
    if(strpos($_SERVER['PHP_SELF'], $url )==false)
    {
      return false;
    }
    else
    {
      return true;
    }
  }






public function DisplayButton($width, $name, $url, $active = true)
  //outputs a single menu button if button is to point to the page to are on, you display an inactive button
#I think width just gives the table cell a % value.  $name involves a setter function declared up top? ,
  {
    if ($active)
    {
      echo "<td width ='$width%'>
            <a href ='$url'>
            <img src ='s-logo' alt ='$name' border ='0' /></a>
            <a href ='$url'><span class='menu'>$name</span></a></td>";
    }  
    else
    {
      echo "<td width ='$width%'>
            <img src ='side-logo.gif'>
            <span class='test'>$name</span></td>";
    }  
  }

Answer 1

Probably this is missing the class declaration, but we move on...

Below, is where your class attributes are declared.

public $content;
public $title = 'TLA Consulting Pty Ltd';
public $keywords = 'TLA Consulting, Three Letter Abbreviation, 
               some of my best friends are search engines';
public $buttons = array( 'Home'     => 'home.php', 
                    'Contact'  => 'contact.php', 
                    'Services' => 'services.php', 
                    'Site Map' => 'map.php'
                  );

__set() is a magic method from PHP. You can check all of them here later. We'll focus on __set() . It means that every time you set an attribute in your object it will define and set this attribute, even if you haven't declared it on your class.

// class Page's operations
public function __set($name, $value)
{
    $this->$name = $value;
}

Next, we have DisplayMenu , which renders the menu on screen. The $width , means the width of each button. So, if you have 4 buttons in $buttons , it will split up the space, which in this case is 100%, among them, thus, resulting in 25% for each button.

public function DisplayMenu($buttons)
{

    echo "<table width='100%' bgcolor='red' cellpadding='3' 
            cellspacing='4'\n";
    echo "  <tr>\n";

    $width = 100/count($buttons);

    while (list($name, $url) = each($buttons))
    {
        // This will render the button on screen.
        // Params:
        // 1 The width of the button.
        // 2 The name of the button.
        // 3 The url the button points to.
        // 4 Checks if the button url is the same url of the current page. 
        $this->DisplayButton($width, $name, $url, !$this->IsURLCurrentPage($url));
     }
     echo "  </tr>\n";
     echo "</table>\n";
}

IsURLCurrentPage method checks if the $url passed as argument is the current URL and returns true or false. True if it is the current page, false if not.

public function IsURLCurrentPage($url)
{
    if (strpos($_SERVER['PHP_SELF'], $url )==false)
    {
        return false;
    }
    else
    {
        return true;
    }
}

And finally, DisplayButton will render the actual button. Each one of them is rendered individually.

public function DisplayButton($width, $name, $url, $active = true)
{
    // This will, in practice verify for you if 
    // the current page is the same of the button the user clicked. 
    // If it is, it will display the button without the link for that 
    // button, or with a disabled link. 
    // You'll notice it will show differently. Maybe 
    // also with some different color or style according to the CSS class.
    // Remember that $active is the result of the IsURLCurrentPage().

    if ($active)
    {
        echo "<td width ='$width%'>
              <a href ='$url'>
              <img src ='s-logo' alt ='$name' border ='0' /></a>
              <a href ='$url'><span class='menu'>$name</span></a></td>";
    }  
    else
    {
        echo "<td width ='$width%'>
              <img src ='side-logo.gif'>
              <span class='test'>$name</span></td>";
    }  
}