Re: Drop doesn't work after createBegin:,createEnd:

[Rick Riolo]

Hi Benedikt,
I tried what I think is a very simple test of what you did 
(almost..see below) and I don't get a crash.

Here is my main.m (i've left out imports, etc):

int main(int argc, char ** argv) {
  id  bug;

  initSwarm(argc, argv);

  bug = [Heatbug1 createBegin: globalZone];
  [bug setIdealTemperature: 100];
  [bug setOutputHeat: 110];
  bug = [bug createEnd];

  [bug printSelf];

  printf("\ngetIdealTemperature -> %d.\n", 
    [bug getIdealTemperature] );

  [bug drop];

  printf("just dropped the bug...bye!\n");

  return 0;
}
---------------------------------------------------------------
Here is the interface:

@interface Heatbug1: SwarmObject {
  double     unhappiness;               
  HeatValue  idealTemperature;
  HeatValue  outputHeat;                
}
-createEnd;
-(double) getUnhappiness;
-(HeatValue) getIdealTemperature;
-(HeatValue) getOutputHeat;
-(void) setIdealTemperature: (HeatValue) i;
-(void) setOutputHeat: (HeatValue) o;
-(void) printSelf;
@end
------------------------------------------------------------------
Here is the Heatbug1.m:
 
@implementation Heatbug1

-createEnd { return self; }

-(double) getUnhappiness { 
    return unhappiness; }
-(HeatValue) getIdealTemperature { 
    return idealTemperature; }
-(HeatValue) getOutputHeat { 
    return outputHeat; }

-(void) setIdealTemperature: (HeatValue) i {
  idealTemperature = i; }
-(void) setOutputHeat: (HeatValue) o {
  outputHeat = o; }

-(void) printSelf {
  printf( "printSelf Heatbug values:\n" );
  printf( "  unhappiness:      %.2f\n", unhappiness );
  printf( "  idealTemperature: %d.\n", idealTemperature );
  printf( "  outputHeat:       %d.\n", outputHeat );
}

@end
------------------------------------------------------------------
Here is a run:

badger-rlr)heatbugs1
printSelf Heatbug values:
  unhappiness:      0.00
  idealTemperature: 100.
  outputHeat:       110.

getIdealTemperature -> 100.
just dropped the bug...bye!
badger-rlr)
------------------------------------------------------------------
So what are the differences between what I did and what you did:
1) I createBegin in the globalZone directly 
   (since this is not happening inside another object, so I can't
    do a [self getZone]).
2) My createEnd doesn't do anything except return self.
3) Lots of other stuff, since my example is so simple...

I modified the above program by adding a -createABug method,
which just does:
-createABug {
  id bug;
  printf("ask a bug to create a bug...\n");
  bug = [Heatbug1 createBegin: [self getZone]];
  [bug setIdealTemperature: 100];
  [bug setOutputHeat: 110];
  bug = [bug createEnd];
  [bug printSelf];
  [bug drop];
  printf("\nthe created sub-bug now dropped.\n");
  return self;
}

So in main.m before I drop the bug, I ask it to createABug
and drop it.  That works ok too, at both levels,
so I don't think its connected to [self getZone].

So....I must be missing something from your examples.
Is my createEnd not doing something that yours does?
Am I missing something else?

 - r

ps this is all swarm-1.0.5 .

Rick Riolo                           address@hidden
Program for Study of Complex Systems (PSCS)
4068 Randall Lab                
University of Michigan         Ann Arbor MI 48109-1120
Phone: 313 763 3323                  Fax: 313 763 9267
http://www.pscs.umich.edu/PEOPLE/rlr-home.html

On Fri, 30 Jan 1998, Benedikt Stefansson wrote:

> Date: Fri, 30 Jan 1998 19:21:50 -0800
> From: Benedikt Stefansson <address@hidden>
> To: address@hidden
> Subject: Drop doesn't work after createBegin:,createEnd:
> 
> Hi,
> 
> I guess Roger is the one to answer this one.  It's one of my pet peeves
> with Swarm, and I've never been able to figure it out from the docs.
> 
> Here's the deal: If you override the createEnd: method with your own and
> use the
> 
> agent=[Agent createBegin: [self getZone]];
> (set some parameters)
> agent=[agent createEnd]
> 
> form, and later call [agent drop] on this agent, you get a run-time
> error, and SIGABRT crash. The crash message looks like this:
> 
> error: Zone_c.Creating (class)
> Zone_c.Creating does not recognize dropAllocations:
> 
> Now, if I change the -createEnd method name in the agent to something
> like "initialize" and use
> 
> agent=[Agent create: [self getZone]];
> (set some parameters)
> agent=[agent initialize];
> 
> the subsequent [agent drop] call works. Seems odd and inconsistent to
> me, and the docs make no mention of it.
> 
> I think that this defies the whole purpose of introducing two different
> "protocols" for creating objects in the first place, i.e.simple create
> vs. createBegin,createEnd
> 
> I guess my question is, is this a bug or a feature?
> 
> Regards,
> -Benedikt
> 
> ------------------
> Benedikt Stefansson                 address@hidden
> Department of Economics, UCLA       Fax. (310) 825-9528
> Los Angeles, CA 90095-1477          Tel. (310) 825-4126
> 
> 
> 
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