Re: XForms: In 0.86 - fl_hide_object(input) calls callback ?

Richard Kent (kent@hydra.dra.hmg.gb)
Fri, 15 Aug 1997 09:28:55 +0100

To subscribers of the xforms list from "Richard Kent" <kent@hydra.dra.hmg.gb> :

> >As far as I can tell, the problems seem to be associated with
> >calls to fl_hide_object() on an input object. One thing I noticed
> >was that the callback associated with that object gets called
> >during the call to fl_hide_object(). This seems odd, no ?
>
> Depending how you look at it. Hiding an input object or a form
> with input object on it is considered an input focus change
> and in most cases, invoking the callback is the correct
> behavior. Perhaps the manual should make this clear.

I have to admit I came across this problem fairly recently (apologies for not
writing to the list). It took me approximately a whole week to work out that my
program was crashing on initialisation because I was hiding some input objects
in my "initialise" routine - which then called the appropriate input callbacks
- which then tried to access data structures which weren't yet initialised -
immediate core dump !!

I have to say (for the first time ever in fact !!) I don't agree with TC. There
are a couple of reasons :-

* Initialisation - as stated above, if you try and hide an input object ready
for the start of your program you DON'T want the callback to be called yet.

* Consistency - when you hide any other object (browser, button, etc) its
callback is NOT called - why should input objects be a special case ?

* Intuitiveness - to my mind, a callback for any kind of input object should
only be called if the input has been changed. Hiding an input object does not
affect its contents in any way - and thus the callback shouldn't be called -
well I think so ;)

I see a thread starting..... :))

Cheers,

TicH

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| Name - Richard Kent (TicH) |
| EMail (work) - kent@hydra.dra.hmg.gb |
| The brain is a wonderful organ; it starts working the moment you |
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