Re: functions vs methods
Re: functions vs methods
- Subject: Re: functions vs methods
- From: Ondra Cada <email@hidden>
- Date: Fri, 20 May 2005 01:28:06 +0200
Ouch!
On 20.5.2005, at 0:54, Sean McBride wrote:
Given one of my classes, Foo, how can I define a function (not
method)
post() which accesses an instance variable textView of Foo? The
following doesn't work:
You might find this thread useful:
<http://www.cocoabuilder.com/archive/message/cocoa/2003/7/3/80660>
Rather not! I've read five or six messages from the thread and I
regret to say nearly all the writers are patently wrong.
It's quite simple: far as functions per se go, ObjC directives have
*no* effect at all. Put a function outside or inside @implementation/
@end, there's no difference *at all*. And, presumed the function is
in a .m (or .M, for ObjC++) file, you can freely use messaging
inside. Again, regardless @implementation's, even regardless there's
any.
The only difference (which has a little to do with functions, it
works more or less the same way in methods) is that code inside
@implementation/@end is allowed to access the class' protected and
private properties directly, whilst code outside of them is not. Thus:
9 /tmp> >q.m
#import <Foundation/Foundation.h>
@interface A {
@public int public;
@protected int protected;
@private int private;
}
@end
void f1(A *a) {
printf("%d",a->public); // OK
printf("%d",a->protected); // Wrong
printf("%d",a->private); // Wrong
}
@implementation A
void f2(A *a) {
printf("%d",a->public); // OK
printf("%d",a->protected); // OK
printf("%d",a->private); // OK
}
@end
10 /tmp> cc -c q.m
q.m: In function 'f1':
q.m:10: warning: instance variable `protected' is @protected; this
will be a hard error in the future
q.m:11: warning: instance variable `private' is @private; this will
be a hard error in the future
11 /tmp>
---
Ondra Čada
OCSoftware: email@hidden http://www.ocs.cz
private email@hidden http://www.ocs.cz/oc
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