Re: Create an NSCharacterSet constant
Re: Create an NSCharacterSet constant
- Subject: Re: Create an NSCharacterSet constant
- From: Graham Cox <email@hidden>
- Date: Mon, 2 Nov 2009 16:32:49 +1100
On 02/11/2009, at 4:19 PM, John Joyce wrote:
Is it possible to create an NSCharacterSet constant?
Attempting to do so with the methods for creating an NSCharacterSet
naturally fails to compile with "initializer element is not constant"
I would ideally like to be able to do this.
Is it best just to declare a global constant string, then initialize
an NSCharacterSet during app initialization? It certainly seems that
is the only real option.
Am I missing something?
If I am correct in what I am seeing, would there not be a valid use
case for this as an extension of NSCharacterSet?
You can't create any non-scalar constant (except nil) using a static
initializer.
However, what you want to do is super-easy, and yes, it's a case for
an extension to NSCharacterSet. Just add a class method as a category:
@interface NSCharacterSet (MyCharacterSetConstant)
+ (NSCharacterSet*) theConstantCharacterSet;
@end
@implementation NSCharacterSet (MyCharacterSetConstant)
+ (NSCharacterSet*) theConstantCharacterSet
{
static NSCharacterSet* s_tccs = nil;
if( s_tccs == nil )
s_tccs = [[self characterSetWithCharactersInString:@"..."]
retain];
return s_tccs;
}
@end
--Graham
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