Procedural to OOP

Posted on 16th Feb 2014 by admin

John Kleijn said that to avoid writing "crappy code", we should learn OOP and common OO principles. I've started reading OOP tutorials including the design patterns. And John is right, this is not an easy task. It's a shame because I'm finding it hard to absorb the tutorials.

Is it ok if I'll show you some of my procedural codes and you'll show me how to code some of its parts in OOP? I learn faster by playing with relevant codes. I hope it's ok with you guys.


Basically, all my php files look like this:
Code: ini_set('display_errors', 1);
error_reporting(E_ALL & ~E_NOTICE);

include("fxns.php");
define('TITLE', 'Page Title');
session_start();

if(isset($_SESSION['user_id'])) {
if (validate_user() == true) {
print_header(TITLE); // echos html codes
print_navs(); // echos html codes
//contents here
// calling more functions here
print_footer();
}
} else {
header('Location: login.php');
}

and my fxns.php would look like this:
Code: include("connect.php");

function validate_user() {
$sql = "SELECT uo.ip_address, uo.session_id, uo.user_agent, uo.activity
FROM users_online uo, users u
WHERE uo.user_id='$_SESSION[user_id]' AND uo.user_id=u.user_id";
$res = mysql_query($sql); $row = mysql_fetch_array($res);
$ip_address = $row[0];
$session_id = $row[1];
$user_agent = $row[2];
$activity = $row[3];

$res2 = mysql_query("SELECT config_value FROM config WHERE config_name='inactivity'");
$row2 = mysql_fetch_array($res2); $inactivity = $row2[0];

$res3 = mysql_query("SELECT locked, invalid_ip FROM users WHERE user_id='{$_SESSION[user_id]}'");
$row3 = mysql_fetch_array($res3); $locked = $row3[0]; $invalid_ip = $row3[1];

// verify user's IP address
if($ip_address != $_SERVER['REMOTE_ADDR']) {
show_invalid_ip($_SERVER['REMOTE_ADDR']); // echo some HTML
}
// verify if the the session id and user's session id are the same
elseif ($session_id != session_id()) {
show_invalid_sid(); // echo some HTML
}
// verify if the browser software is the same
elseif($user_agent != $_SERVER['HTTP_USER_AGENT']) {
show_invalid_user_agent(); // echo some HTML
}
// verify if the user is locked
elseif ($locked == 1) {
show_locked($invalid_ip); // echo some HTML
}
// verify if the user has been inactive for $inactivity mins
elseif( time() > ( $activity + ($inactivity * 60) ) ) {
show_s_expired($inactivity); // echo some HTML
} else {
update_user();
return true;
}
}

function update_user() {
$maxtime = time() - 1800;
mysql_query("UPDATE users_online SET refurl='{$_SERVER['HTTP_REFERER']}' WHERE user_id='$_SESSION[user_id]'");
mysql_query("UPDATE users_online SET activity='".time()."' WHERE user_id='$_SESSION[user_id]'");
mysql_query("DELETE FROM users_online WHERE activity < '$maxtime'");
}


Would you be kind to write some of its part in OOP? Thanks so much.