dynamic binding?

[James Marshall]

Hi,
  I have a problem when compiling my Swarm app now, because I have 
two objects each with a method of the same name (but taking 
and returning different format parameters (ints or doubles). When I 
try to compile this the compiler warns of the multiple declarations 
and chooses one to use at compile time. Why does this happen? I 
though Objective C was supposed to allow polymorphism and dynamic 
binding? i.e. the method to use should be chosen at run-time, not 
compile time, after examination and determination of the type of the 
object receiving the message? Maybe I've missed out a compiler flag, 
but I'm including the standard (Swarm 1.1) Makefile.appl in my 
makefile?  There follows the complete source for the objects 
concerned, and an example line of code that generates a compiler 
warning for me...
        James

//DoubleData.h Double wrapper for use with arrays

#import <objectbase.h>

@interface DoubleData: SwarmObject
{
  double data;
}

-(double)getData;
-(void)setData: (double) newData;

@end

//DoubleData.m Double wrapper for use with arrays

#import "DoubleData.h"

@implementation DoubleData: SwarmObject
{
  double data;
}

-(double)getData
{
  return data;
}
-(void)setData: (double) newData;
{
  data=newData;
}

@end

//IntegerData.h Integer wrapper for use with arrays

#import <objectbase.h>

@interface IntegerData: SwarmObject
{
  int data;
}

-(int)getData;
-(void)setData: (int) newData;

@end

//IntegerData.m Integer wrapper for use with arrays

#import "IntegerData.h"

@implementation IntegerData: SwarmObject
{
  int data;
}

-(int)getData
{
  return data;
}
-(void)setData: (int) newData;
{
  data=newData;
}

@end

[[alleles atOffset: l1] setData: [[alleles atOffset: 
l1] getData]+(int)[[agent getStrategy] atOffset: l1]];

EPDWorld.m:154: warning: multiple declarations for method `getData'
IntegerData.h:10: warning: using `-(int)getData'
DoubleData.h:10: warning: also found `-(double)getData' 
EPDWorld.m:154: warning: multiple declarations for method `setData:' 
IntegerData.h:11: warning: using `-(void)setData:(int)newData' 
DoubleData.h:11: warning: also found `-(void)setData:(double)newData'
--
James Marshall - Postgraduate Research Student (MPhil/PhD)
Artificial Intelligence Group - Department of Computer and Information Sciences
De Montfort University - Milton Keynes Campus
Web:- http://www.mk.dmu.ac.uk/~jmarshall/

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