MESSAGE
| DATE | 2004-09-10 |
| FROM | Ruben Safir Secretary NYLXS
|
| SUBJECT | Re: [hangout] Re: two dimensional arrays passed to functions
|
> Functions should be kept
> clean enough that it isn't a problem. So abusing goto is
> very bad, but so is abusing any other feature. I know
> that when I use it, it's as a sort of last resort when
> the alternatives would be worse (read: more bug-prone).
>
Like longjump and short jump for errors?
>
> You mean that give Oracle a function pointer to use in case of
> emergency? That's a good idea. I think TCL does that, too.
Something like that. It's been a while, but I think it has it's
own signal that will longjump to a named function.
>
> > In addition, there is always signals, which is how I originally
> handled
> > errors. The thing is here, the 'error' is not necessarily an error.
> It
> > could be a normal response from the database, like an attempt to
> insert
> > already entered data on a unique key. In which case, I want to
> switch
> > over and do an UPDATE instead.
>
> Sound thinking. You're talking about gtk signals or Unix signals?
I meant unix signals, singnals.h I think in the C library. Also,
consider
GTK, in their obsession to force an Object-like notation onto
everything,
one of the benifits is that instead of capturing the whole of a
structured
program in if statements, you should be able to emit a GTk signal to the
top level window, or carry the error handling up the tree, which already
exists, without the need for break break break.
>
> > > You were doing a return if anything went wrong,
> > > and you never cleaned up the MYSQL session, so I suppose you
> didn't
> > > see a need for the goto before.
> >
> > Yeah, it is not apparent yet from the code, but the MYSQL struct
> > instance, there is a flag called reconnect which I want to check
> for. I
> > believe if it is 1, then you need to reconnect. I actually want to
> make
> > that data structure global and to cache the database connection,
> > eventually closing it in the destructor.
>
> Make a big struct (of which the MYSQL connection is one member) and
> pass
> it around everywhere. Much cleaner than using globals...
That's a thought but the last time I did that I had to malloc the
structure
and I really don't know where to free it since it is being used in all
the
lower Widgets. Otherwise it disapears from the tact. That's why, just
for
exepedency, I created those dreadful global structures to store data.
You can't
just create a structure and then passing to the callback function at
g_pointer a
because it disapears from the darn stack. It took me two days to
figure that out this
time, and a week last time (although RMS figured it out in about 15
seconds in the debugger.)
The wild factor here is that gtk_main() is actually interceeding in
everything here. Roughly
speaking, when you click on a button, your talking to gtk_main() which
'senses' the clicked
event and then looks for the proper callback and then runs it. In this
case at least, it
is a darn mine field.
>
> > I don't know what mysql_init(&MYSQL) does, but it does not allocate
> any
> > memory.
>
> One thing it does is allocates space for a MYSQL if you pass it a
> NULL.
>
Say again? Where did you read that? Then why did I have to make sure
the
memory was allowed for it? What the heck does mysql_init() do then.
It completely didn't work otherwise. I'm totally confused now.
> >That is the reason for the assignment of the pointer.
>
> > I hope I'm missing something of the MYSQL API, because otherwise I
> might
> > end up creating a global flagging system in order to cache the
> database
> > connection.
>
> Go for it. But not global define a struct. You'll be happy you did.
>
I need some rest. I feel like I'm back in College again. I've crammed
for finals relearning 2 dimensional arrays, array function parameters,
the string library, the mysql C API, the GTK C API, patch, diff, vi
advanced features
gdb, and C macros all in the last 48 hours, in addition to trying to
remain with a
sane program design and boning up on integration for Biopharmacuetics
all in the last
48 hours. SOMEBODY better be giving me a masters degree when this is
done.
Ruben
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