Why use classes????

Graffiti

This might seem as a dumb question. Maybe it is. I am looking for enlightening 😃.

I am wondering why someone should use classes instead of functions. I could not figure out where the advantages are, although I am sure that there are some.

Can´t I do everything I can do with classes with functions also?

I would be very glad, if someone could give me a kickstart or something.

Thanks
Volker

mmilano

i use classes to organize my code and for re-use mostly. it's also much easier to work with class variables when you are writting your scripts (outside the class) because you don't have to worry about the variables being used by something else in your script.

i will generally make one class do all my data managment. basically everything that manipulates data without printing anything to the screen, .. then i will make an extention class that does all the printing.

lets say i just created an ecommerce site.. the engine of the site is in a "store" class. then i make an extension class called "display" .

if i ever want to create another ecommerce site, i can just use the "store" class. if i want the new store to have a different look, i can just make a new display class .. otherwise, i will use the same display class.

it is more of a workflow thing for me. working with objects is much more organized for me to code with. i didn't realize how great oophp was until i started using it. now i couldn't imagine programming without without it.

<?
class person
{
     function person($name)
     {
           set_name($name);
           $this->favorite_language="PHP";
     }

 function set_name($name)
 {
      $this->name=$name;
 }
}

$me = new person("mike");
echo "my name is " .  $me->name . "<br>";
echo "my favorite language is " . $me->favorite_language . "<br>";
?>

just a small example: if you have a function in the class that is named the same as the class itself "person()" , then that function will execute as soon as the object is created. '$me = new person("mike") '

don't know if i answered your question, but this is just some stuff off the top of my head. don't fear oop, it is great =)

jayant

Classes make the code Object-oriented. As it is object-oriented coding has many advantages. These include:
Data Abstraction
Polymorphism
.....

sarahk

Classes allow you to have more complex grouping of functions.

When you call a function you must pass it certain data or code defaults into the function.

With a class you can have methods to accept data and then run the method which does something and the class knows about itself. It can update other properties for you to access later.

I don't use classes alot as I use phplib templates to control my presentation layer but whole template thing is driven by a class. I load up $t which is my template object with a mountain of data and then ask it to parse and hey presto everything comes out the way I want.

I use a class to manage my database access. I end up passing a global $db around and my code is much cleaner because it knows what it needs to know.

I use a class to manage my emails (which also use the template and wow, html email become so easy).

My mailing list management on the other hand is all done by functions but would so much easier to manage if I knuckled down and rewrote it into a class. I wouldn't need to pass so many variables. I wouldn't need to worry about returning lists and all that stuff. The class could just update itself and be done with it.

Graffiti

Does that mean that you can for example asign values to the class just as they apear and then run the class. The class then rememberes the values you asigned early?

That would indeed be a great advantage.

Thanks for clearifying this.

Volker

tsigo

Originally posted by Graffiti
Does that mean that you can for example asign values to the class just as they apear and then run the class. The class then rememberes the values you asigned early?

Sorta. The values won't carry over from page-to-page, but they will retain their values between separate instances of a class.

You could have one instance of a class and change a variable of that class to one value, and then have another instance of that class and the variable value could be completely different. They would remain separated.

mattuu

Almost all variables in a class will store if you session_register a class object. Not quite everything -- for example, you can't session store a mysql result set -- but almost. One caveat, however, is that you must include the definition of the class before running session_start(), or you'll get an error.