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/**
STUndefinedObject.m
Wrapper for nil object
Copyright (c) 2002 Free Software Foundation
Written by: Stefan Urbanek <urbanek@host.sk>
Date: 2000
This file is part of the StepTalk project.
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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#import "STUndefinedObject.h"
#import "STExterns.h"
#import "STObjCRuntime.h"
#import <Foundation/NSString.h>
#import <Foundation/NSInvocation.h>
#import <Foundation/NSMethodSignature.h>
STUndefinedObject *STNil = nil;
@implementation STUndefinedObject
+ (id) alloc
{
return STNil;
}
+ (id) allocWithZone: (NSZone*)z
{
return STNil;
}
+ (id) autorelease
{
return self;
}
- (void) dealloc
{
NSLog(@"Warning: Trying to dealloc STNil object");
}
- (NSMethodSignature *)methodSignatureForSelector:(SEL)sel
{
NSMethodSignature *signature = nil;
signature = [super methodSignatureForSelector:sel];
if(!signature)
{
signature = STConstructMethodSignatureForSelector(sel);
}
return signature;
}
- (void) forwardInvocation: (NSInvocation*)anInvocation
{
/* this object is deaf */
/* Nevertheless, it must clear the invocation's result, which may contain
random contents under GNUstep. That could lead to a crash if the
expected result is an object. */
NSMethodSignature *signature = [anInvocation methodSignature];
NSUInteger n = [signature methodReturnLength];
if (n > 0)
{
char buffer[n];
memset(buffer, '\0', n);
[anInvocation setReturnValue: buffer];
}
}
- (BOOL) isEqual: (id)anObject
{
return ( (self == anObject) || (anObject == nil) );
}
- (oneway void) release
{
/* do nothing */
}
- (id) retain
{
return self;
}
- (BOOL)isNil
{
return YES;
}
- (BOOL)notNil
{
return NO;
}
@end
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