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/** Implementation for NSNull for GNUStep
Copyright (C) 2000 Free Software Foundation, Inc.
Written by: Richard Frith-Macdonald <rfm@gnu.org>
Date: 2000
This file is part of the GNUstep Base Library.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free
Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110 USA.
<title>NSNull class reference</title>
$Date$ $Revision$
*/
#import "common.h"
#import "Foundation/NSNull.h"
/**
* An object to use as a placeholder - in collections for instance.
*/
@implementation NSNull
static NSNull *null = 0;
+ (id) allocWithZone: (NSZone*)z
{
return null;
}
+ (id) alloc
{
return null;
}
+ (void) initialize
{
if (null == 0)
{
null = (NSNull*)NSAllocateObject(self, 0, NSDefaultMallocZone());
[[NSObject leakAt: &null] release];
}
}
/**
* Return an object that can be used as a placeholder in a collection.
* This method always returns the same object.
*/
+ (NSNull*) null
{
return null;
}
- (id) autorelease
{
return self;
}
- (id) copyWithZone: (NSZone*)z
{
return self;
}
- (id) copy
{
return self;
}
- (void) dealloc
{
GSNOSUPERDEALLOC;
}
- (NSString*) description
{
return @"<null>";
}
- (void) encodeWithCoder: (NSCoder*)aCoder
{
}
- (id) initWithCoder: (NSCoder*)aCoder
{
return self;
}
- (BOOL) isEqual: (id)other
{
if (other == self)
return YES;
else
return NO;
}
- (oneway void) release
{
}
- (id) retain
{
return self;
}
@end
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