le 2001/06/09 22:28, Hans van Maanen à hans@... a écrit :

> 
> Hans "never write more than you need" van Maanen

as programmers we have responsability to our users. if that user is you -
damn the torpedos. but even in that case there is an argument that you
should use correct programming practise, as the day you cut and paste a line
or two, you may not remember that you left out all error checking.

to answer your remarks:

> So if 
> th& = 0, there's little I can do anyway. Can I?

From what i understand, if the handle is empty, then there is nothing on the
clipboard. so this is a prefectly normal situation.
where there is something on the clip then it would replace content elsewhere
and your cancel function should take this into account. if the clip is
empty, then you would just gracefully exit as this is unneeded.

> e = FN HLOCK()
> LONG IF e = _noErr
> ...
> END IF
> 
> Why not just:
> 
> e = FN HLOCK()
> ...
> e = FN HUNLOCK()
> 
> and damn the consequences. What say you?

here i would disagree further, even with the talented programmers who have
counseled you so far, i would 98% of the time get the handle state, save
that state, lock the handle, check the error, and at the end restore it to
the previous state. this is such an automatic choice that you should have a
tinplate function to do that. i have stated this many times in the past [but
perhaps you weren't around them... i mean in those days the fblist was just
scratched up on a cave door somewhere... :-) ]

[BTW. is e = _noErr still valid? I thought that that had changed?]

is it important to check for errors? yes siree. whether you are using 30Kb
of memory or 3Gb. If you can't get the memory you need, or you can't
manipulate it as you need, you should inform your user and gracefully bail
out. this will never happen of course, but the time it does happen your user
will be happy that you did it.

has it also ocurred to you that perhaps your app is fine, but that another
app is running rampage over the memory and trampling in your area? [this
will happen even under OS X, as classic apps all share the same memory
place. it won't bring the X space down, but it will mess up the classic
box.]

And you can't go complaining about that other wild app, if you don't program
to the rulebook either!

A long time ago i wrote a memo on recovering gracefully from errors... i'll
try and dig it up, update and repost.

:-j