I've used this when compiling code for both 10.6 and below to avoid
protocol errors. Seems to do the trick.
Kevin
On Jun 2, 2010, at 8:57 AM, Matt Neuburg <[email protected]> wrote:
Here's something I stumbled on by accident. Consider the following:
// MyClass.h
#import <Foundation/Foundation.h>
@interface MyClass : NSObject {
}
@end
// MyClass.m
#import "MyClass.h"
@implementation MyClass
- (void) testing {
NSLog(@"testing");
}
@end
// UnadoptedProtocolAppDelegate.h
#import <Cocoa/Cocoa.h>
... // skipping irrelevant stuff
@protocol Unadopted
- (void) testing;
@end
// UnadoptedProtocolAppDelegate.m
#import "UnadoptedProtocolAppDelegate.h"
#import "MyClass.h"
@implementation UnadoptedProtocolAppDelegate
- (void)applicationDidFinishLaunching:(NSNotification *)
aNotification {
MyClass* mc = [[MyClass alloc] init];
[(id)mc testing];
}
@end
This compiles and runs fine, even though MyClass never adopted the
protocol
Unadopted. It take it that by casting mc to an id, I cause the
compiler to
grasp at the only signature for "testing" that it knows about,
namely the
one in the protocol. So it happily uses that signature without
complaint,
and at runtime the correct message is sent to the MyClass instance.
So this appears to be a technique for implementing a highly informal
protocol. (The technique is: define a protocol, don't bother
adopting it
anywhere, but send messages defined in that protocol to an id.) My
question
is, is this technique:
(a) pointless and lazy
(b) sneaky and clever
(c) just a mistake all round
(d) well known; you only just noticed this??
(e) all of the above
(f) none of the above
:) m.
--
matt neuburg, phd = [email protected], <http://www.tidbits.com/matt/>
A fool + a tool + an autorelease pool = cool!
AppleScript: the Definitive Guide - Second Edition!
http://www.tidbits.com/matt/default.html#applescriptthings
_______________________________________________
Cocoa-dev mailing list ([email protected])
Please do not post admin requests or moderator comments to the list.
Contact the moderators at cocoa-dev-admins(at)lists.apple.com
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/cocoa-dev/kainjow%40kainjow.com
This email sent to [email protected]
_______________________________________________
Cocoa-dev mailing list ([email protected])
Please do not post admin requests or moderator comments to the list.
Contact the moderators at cocoa-dev-admins(at)lists.apple.com
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com
This email sent to [email protected]
