Basic PHP OOP for Regex Login - What am I doing wrong here?

Question

I am re-learning php after almost 10 years of not using it, and now I want to re-learn it, and correctly this time, but I seem to not be grasping OOP, what am I doing wrong here?

Trying to make a basic login script.

login.php

$act = isset( $_POST['act'] ) ? $_POST['act'] : '' ;

switch ($act) {
case 'login':

$uname = new CleanData($_POST['username']);
$uname-> set_minlength('8');
$uname-> set_maxlength('40');
$uname-> set_pregtype('match');
$uname-> set_regex('/^[\w@._-]{8,40}$/');
$uname-> cleaner();

etc...

class file

class CleanData
{
var $data;
var $minlength;
var $maxlength;
var $pregtype;
var $regex;

function __construct($data)
{
    $this->data = $data;
}

function set_minlength($minlength){
    $this->$minlength = $minlength;
}

function set_maxlength($maxlength){
    $this->$maxlength = $maxlength;
}

function set_pregtype($pregtype){
    $this->$pregtype = $pregtype;
}

function set_regex($regex){
    $this->$regex = $regex;
}

function cleaner(){

    print $this->pregtype."\n";

    if ($this->pregtype == 'match') {
        print "MATCH REGEX HERE";
    }elseif ($this->pregtype == 'replace') {
        print "REPLACE REGEX HERE";
    }else{
        print "UNKNOWN REGEX TYPE";
    }

}

}

I get "UNKNOWN REGEX TYPE", which I am sure makes perfect sense, but I dont understand why. Am I even using OOP correctly by writing this class?

Its really hard to re-learn something correctly after doing it wrong, I just want to write it fast the way I know how instead of re-learning everything and writing at a snails pace, but I must stay strong...

I appreciate the help, I always wanted to post here, but I suck at asking for help, always want to do everything myself.

Answer 1

$this->$minlength = $minlength;
       ^----NO, don't do this

You're trying to set a dynamic attribute based on your argument, which makes no sense at all. eg

set_minlength(42)  -> `$this->42 = 42`
set_maxlength(42)  -> `$this->42 = 42`

Now you've not only overwritten the minlength value, you have no way of know what the heck this mysterious $this->42 really is. How would get_minlength() work? $this->???? ?

Try

$this->minlength = $minlength;
       ^---note, no $

and similar for all of your OTHER methods as well.

Answer 2

Try to change these:

$this->minlength = $minlength;

$this->maxlength = $maxlength;

 $this->pregtype = $pregtype;

 $this->regex = $regex;

Here you are assigning the values to the variables, that are declared above.