[plt-scheme] Need more class examples?

Hello,

This code :

(define my-area% (class* object% (area<%>)
                   (init min-width)
                   (define mini-width min-width)

                   (define/public (get-top-level-window)
                     this)
                   (define/public (get-parent)
                     #f)
                   (define/public (stretchable-height)
                     #f)
                   (define/public (stretchable-width)
                     #f)
                   (define/public (get-graphical-min-size)
                     0)
                   (define/public (min-width)
                     0)
                   (define/public (min-height)
                     0)
                   (super-new)))

complains :
"class*: duplicate declared identifier in: min-width "

My question is how you implement class method and init variable with same name?
I tried to read the class reference manual , but its too complex for
me at the moment, so some examples
will be of great help.

Thanks