Re: adding something to a setter
Re: adding something to a setter
- Subject: Re: adding something to a setter
- From: glenn andreas <email@hidden>
- Date: Thu, 06 Oct 2011 08:29:38 -0500
On Oct 6, 2011, at 6:28 AM, Torsten Curdt wrote:
> The property syntax is great until you need one more thing.
>
> Think of a NSView and that view displays a value.
>
> @synthesize value;
>
> Now you also want to setNeedsDisplay: when a new value is set. So one
> can override the setter.
>
> - (void)setValue:(NSString*)theValue
> {
> ...
> [self setNeedsDisplay:YES];
> }
>
> but - you would have to implement the setter yourself. No big deal -
> but... it sucks.
> Is there a way to forward the setting to the originally synthesized
> setter? Super cannot be it.
>
> Of course one could add another selector that to the interface
>
> - (void) setValueAndUpdateDisplay:(NSString*)theValue
> {
> self.value = theValue;
> [self setNeedsDisplay:YES];
> }
>
> ...but that sucks, too.
>
> There gotta be a better way!
> How do you deal with this?
In your .m file, inside either the class extension or an "internal use only" class category, declare:
@property (nonatomic, retain) NSString *sideEffectFreeValue; // or whatever property specifier were on the original property
and then synthesize it to use the original ivar
@synthesize sideEffectFreeValue=value;
and change your setter to:
- (void) setValue: (NSString *) value
{
self.sideEffectFreeValue = value;
[self setNeedDisplay: YES];
}
Glenn Andreas email@hidden
The most merciful thing in the world ... is the inability of the human mind to correlate all its contents - HPL
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