Recursive delete for blogs and forums

Let's say, you've developed a blog or forum and you need to delete some entries. You will also want to delete the responses to those entries. In this example we'll use a table structure like this, where 'refid' is a field used to associate a response with it's referer :
`id`
`refid`
`userid`
`title`
`content`
`tags`
`created`
In our PHP we want to go through each blog entry which we'd like to delete and ascertain it's responses identified by 'refid' before deleting it. Thus :
function deleterecursiveblog($id)
  {
    $q = "SELECT * FROM `blog` WHERE `refid`='{$id}'";  
    $result = mysqli_query($con,$q);
    if(isset($result))
    {
      foreach($result as $key)
      {
        deleterecursiveblog($key['id']);  
      }
    }
    $q = "DELETE FROM `blog` WHERE `id`='{$id}'";  
    $result = mysqli_query($con,$q);
  }

Bash techniques

I've been doing a lot of work in bash lately. I've been speeding up the time taken to create the website basics. Right now I can create a Twitter Bootstrap/Modernizr website with blogs etc within a couple of seconds by calling my bash script. So, below are some techniques I've learned along the way:
Prep-end all slashes in a web address with backslashes
webdir=`echo $webdir | sed s,/,\\\\\\\\\\/,g`
Get the last substring from a string separated by slashes
dbn=${longstring##*/}
Put the contents of a .sql into a database
mysql -u root -p password $dbn < $workingdir"/users.sql"
Change a line within a .ini file
sed -i -e '/DB_NAME =/ s/= .*/= '$dbn'/' config.ini
Hope they help!

Error reporting in PHP

I've seen quite a few blogs which go into great depth about error reporting in PHP. What I and almost everyone else wants when something is going wrong is... Tell me everything. So, here are the lines to put at the top of your .php file
<?php
ini_set('display_errors',1);
ini_set('display_startup_errors',1);
error_reporting(-1);
?>
Job done.

OOP Series : Interfaces

An interface is a template of mthods. Not properties. An interface is usually accompanied by an 'implements' clause. Classes which implement an interface must contain the declared methods. There is no defined means of declaring a JavaScript interface/implments combination.
PHP : template.class.php
<?php
interface template
{
function setWidth($width);
function setHeight($height);
}
?>
PHP : document.class.php
<?php
require_once 'template.class.php';
class document implements template
{
public $width, $height;
function setWidth($width)
{
$this->width = $width;
}

function setHeight($height)
{
$this->height = $height;
}
}
?>
Now a file (index.php) which creates a document object.
<?php
require_once 'document.class.php';
$doc = new document;
$doc->setWidth(10);
$doc->setHeight(10);
echo $doc->width.' '.$doc->height;
?>

OOP Series : Abstraction

Abstract classes are particularly useful if you are working in a team and on a large project. They allow the architect to specify what needs to be available in child classes without saying how. They can also be used to specify methods which must be available to all child classes. Abstract classes should't really be called, just referenced. In the example below I have an abstract class of book and a child class of childrensbook. The good news for me in writing the blog post is that there is no abstract class implementation in JavaScript.
PHP : book.class.php
<?php
/* You may only have child classes of this class */
abstract class book
{
function cover()
{
/* All child classes must have this function */
return 'Nice bright cover';
}

/* Must exists in a child class, but you can implement it as you see fit */
abstract function pages();
}
?>
PHP : childrensbook.class.php
<?php
require_once 'book.class.php';
class childrensbook extends book
{
function pages()
{
return 20;
}
}
?>
Now a file (index.php) which creates a childrensbook object.
<?php
require_once 'childrensbook.class.php';
$achildrensbook = new childrensbook;
echo $achildrensbook->cover().'<br />';
echo $achildrensbook->pages().'<br />';
?>

OOP Series : Encapsulation

One of OOP's strengths is that it provides control over access to properties and methods. This becomes particularly useful when developers are working together and extending classes.It is also often referred to as data hiding. It achieves this through public, private and protected properties and methods. How these are implemented in different languages can vary significantly as you see in the code examples below.
Public usually means anything which makes use of the class can access it.
Private usually means only the class can access it.
Protected usually means either it can access private properties and methods whose values can then be passed back, or can be used only by extended classes.
Given the more complex nature of protected, I tend to use it only when necessary.
PHP : car.class.php
<?php
class car
{
public $mypublicvariable;
private $myprivatevariable;
protected $myprotectedvariable;
function __construct()
{
$this->mypublicvariable = 'guitar';
$this->myprivatevariable = 'beer';
$this->myprotectedvariable = 'chocolate';
}
}
?>
PHP : extendedcar.class.php
<?php
require_once 'car.class.php';
class extendedcar extends car
{
function __construct()
{
parent::__construct();
}

function showprotected()
{
return $this->myprotectedvariable;
}
}
?>
JavaScript : car.class.js
car = function()
{
this.mypublicvariable = 'guitar';
var myprivatevariable = 'beer';

this.myprivilegedmethod = function()
{
return myprivatevariable;
}
}
Now a file (index.php) which creates 2 PHP objects. One from the parent class and one from the extended class. Then 1 JavaScript object.
<?php
require_once 'car.class.php';
require_once 'extendedcar.class.php';
$mycar = new car;
$myextendedcar = new extendedcar;
echo $mycar->mypublicvariable.'<br />';
echo $myextendedcar->showprotected().'<br />';
?>
<script src="car.class.js"></script>
<script>
var mycar = new car();
document.write(mycar.mypublicvariable+'<br />');
document.write(mycar.myprivilegedmethod()+'<br />');
</script>

OOP Series : Inheritance

One of OOP's strengths is that it provides the concept of inheritance. This becomes particularly useful when developers are working together and extending classes. In this first example I'm not going to focus on controlling the visibility of properties and methods. Everything will be public. Visibility will be covered in another blog entry.
PHP:car.class.php
<?php
class car
{
public $mypublicvariable;
function __construct()
{
$this->mypublicvariable = 'guitar';
}
function changevalue()
{
$this->mypublicvariable = 'beer';
}
}
?>
PHP:extendedcar.class.php
<?php
require_once 'car.class.php';
class extendedcar extends car
{
function __construct()
{
parent::__construct();
}
function changevalue()
{
$this->mypublicvariable = 'chocolate';
}
}
?>
JavaScript:car.class.js
car = function()
{
this.mypublicvariable = 'guitar';
}
car.prototype.changevalue = function()
{
this.mypublicvariable = 'beer';
}
JavaScript:extendedcar.class.js
extendedcar = function()
{
car.call(this);
}
extendedcar.prototype = new car();
extendedcar.prototype.constructor = car;
extendedcar.prototype.changevalue = function()
{
this.mypublicvariable = 'chocolate';
}
Now a file (index.php) which creates an object from both.
<?php
require_once 'car.class.php';
require_once 'extendedcar.class.php';
$mycar = new car;
$myextendedcar = new extendedcar;
echo $mycar->mypublicvariable.'<br />';
$mycar->changevalue();
echo $mycar->mypublicvariable.'<br />';
echo $myextendedcar->mypublicvariable.'<br />';
$myextendedcar->changevalue();
echo $myextendedcar->mypublicvariable.'<br />';
?>
<script src="car.class.js"></script>
<script src="extendedcar.class.js"></script>
<script>
var mycar = new car();
var myextendedcar = new extendedcar();
document.write(mycar.mypublicvariable+'<br />');
mycar.changevalue();
document.write(mycar.mypublicvariable+'<br />');
document.write(myextendedcar.mypublicvariable+'<br />');
myextendedcar.changevalue();
document.write(myextendedcar.mypublicvariable+'<br />');
</script>