using PHP classes ... when?

Hi there,

I have been using PHP for a few years but never used classes. I
understand how they are created and how they work but was unsure about
when you use them.

Any help? Cheers

Burnsy

> I have been using PHP for a few years but never used classes. I[color=blue]
> understand how they are created and how they work but was unsure about
> when you use them.[/color]

Classes are basically constructions of variables with some specific
functions added to them. Organizing your data in this way greatly improves
reuse of code and readibility (if applied properly). I suggest you visit the
free repository http://phpclasses.org where all of PHP's possibilities are
exemplified in classes complete with example scripts.

bissatch@yahoo.co.uk wrote:
[color=blue]
> Hi there,
>
> I have been using PHP for a few years but never used classes. I
> understand how they are created and how they work but was unsure about
> when you use them.
>
> Any help? Cheers
>
> Burnsy[/color]

Hi Burnsy,

Classes/Objects are a great way to bundle some functionality in a ordered
way.
You don't have to worry about namespaces and such.
A good designed class will expose its functionality and you don't have to
worry each time you use it HOW that functionality is excactly implemented.

Great for reuse of functionality/code.

Another good thing is the fact that a class can hold its own set of internal
variables. Unlike a function, which forgets it variables when finished, an
object is more persistent and will remember all important variables for its
functioning. (Untill you destroy it of course)

Of course it is perfectly possible to screw things up with a class too. :P

Regards,
Erwin Moller

If you want to download a complete sample application that uses class then
take a look at http://www.tonymarston.net/php-mysql...plication.html
There are plenty of other articles on my site which give info on OOP.

--
Tony Marston

http://www.tonymarston.net



<bissatch@yahoo.co.uk> wrote in message
news:1102676617.049332.57740@c13g2000cwb.googlegro ups.com...[color=blue]
> Hi there,
>
> I have been using PHP for a few years but never used classes. I
> understand how they are created and how they work but was unsure about
> when you use them.
>
> Any help? Cheers
>
> Burnsy
>[/color]

On Fri, 10 Dec 2004 18:32:39 -0000, "Tony Marston"
<tony@NOSPAM.demon.co.uk> top posted like a moron and wrote:
[color=blue]
>If you want to[/color]

read advertisments, I'll by a newspaper.

--
gburnore@databasix dot com
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<bissatch@yahoo.co.uk> wrote in message
news:1102676617.049332.57740@c13g2000cwb.googlegro ups.com...[color=blue]
> Hi there,
>
> I have been using PHP for a few years but never used classes. I
> understand how they are created and how they work but was unsure about
> when you use them.
>
> Any help? Cheers
>
> Burnsy
>[/color]

Well, if you haven't use classes then you probably don't need them for what
you're doing. Usually it's self-evident when using a class is appropriate.
In the case of basic web application development in PHP, there aren't that
many instances where it brings much benefit.

Objects are good for managing states. For example, I like to use objects to
hold data coming from the database. Fields are exposed as object properties
which my application code can freely get and set. Each object internally
keeps copies of the original values, so that when it comes time to save the
data back to the database I can easily tell which fields have changed and
which have not.

A crude example:

class User {
var $user_id;
var $user_name;
var $first_name;
var $last_name;

var $org_user_name;
var $org_first_name;
var $org_last_name;

function User($row = false) {
if($row) {
$this->user_id = $row['user_pk'];
$this->first_name = $this->org_first_name = $row['first_name']
// ... and so on
}
}

function Save() {
if(!$this->user_id) {
// no primary key, meaning we need to do an insert
}
else {
if($this->first_name != $this->org_first_name) {
// add to update list
}
// ... and so on
}
}
}

Situations where a PHP script need to remember state information don't
happen very often though. Most of the time things are calculated, echo'ed to
the client, and quickly discarded. Simple functions serve you well enough.