[racket] gui application needs to perform operation upon closing of a window

[Zelah Hutchinson]

From the documentation I gather that I need to augment the on-close method. I do not understand how to do this. Can someone show me a tiny example of how to perform an operation when a window is closed? Thank you.

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[Matthias Felleisen]

Here we go:

#lang racket/gui

(define my-frame%
(class frame%
(super-new)
(define/augment (on-close)
(displayln "closing now"))))

(define frame
(new my-frame% [label "on closing"][width 300][height 200]))

(send frame show #t)

[Stephen Chang]

I was about to reply with the same answer as Matthias, but with
define/override instead of define/augment, but I kept getting an
error. Does it say anywhere in the docs whether a method is declared
using pubment or public? I couldnt find it.

[Matthias Felleisen]

From the docs:

"
method
(send a-top-level-window on-close) → void?

Refine this method with augment.
...

[Stephen Chang]

Ah ok I see now. I didn't look hard enough.

I saw the "frame%" so I was clicking around here:
http://docs.racket-lang.org/tools/drracket_unit.html?q=on-close#%28meth._%28%28%28lib._drracket%2Ftool-lib..rkt%29._drracket~3aunit~3aframe~25%29._on-close%29%29

On Wed, May 22, 2013 at 7:59 PM, Matthias Felleisen

[Robby Findler]

Thanks, I've fixed those docs.

Robby