[swarm-hackers] Re: Still learning the framework...

On Tue, Nov 17, 2009 at 2:32 PM, Nima Talebi <address@hidden> wrote:

Hi All,

This bit of code about to be presented is merely a proof-of-concept (POC) for myself in learning the framework, and specifically the memory zoning.

What I have here, is an attempt to create a new "HeatbugsWorld", which hides details such as....

* The fact that it "is-a" Swarm
* it conforms to Grid2d

...and adds a few utility methods, for example...

@class HeatbugsModel;

@protocol HeatbugsWorld
- (HBLength)width;

- (HBLength)height;
- (HBSize)size;
@end

@interface HeatbugsWorld:Swarm <Grid2d> {
   HBSize size;

}

+ (id)createBegin:(id)aZone withModel:(HeatbugsModel *)m andSize:(HBSize)s;

- (HBLength)width;
- (HBLength)height;
- (HBSize)size;

@end

@implementation HeatbugsWorld

+ (id)createBegin:(id)z withModel:(HeatbugsModel *)m andSize:(HBSize)s {
   HeatbugsWorld *this = [Grid2d create:m setSizeX:(int)s.width Y:(int)s.height];

   /*! Now set up the grid used to represent agent position... */
   this->size = s;
   return self;
}

- (HBLength)width {

   return size.width;
}

- (HBLength)height {
   return size.height;
}

- (HBSize)size {
   return size;

}

@end

...however, that crashes on `[Grid2d create:m setSizeX:(int)s.width Y:(int)s.height];'. The stack & crashlog...

2009-11-17 14:20:40.679 Heatbugs[1157:6807] +[HeatbugsModel allocIVars:]: unrecognized selector sent to class 0xa3b0

2009-11-17 14:20:40.680 Heatbugs[1157:6807] An uncaught exception was raised

2009-11-17 14:20:40.680 Heatbugs[1157:6807] +[HeatbugsModel allocIVars:]: unrecognized selector sent to class 0xa3b0

2009-11-17 14:20:40.682 Heatbugs[1157:6807] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '+[HeatbugsModel allocIVars:]: unrecognized selector sent to class 0xa3b0'

*** Call stack at first throw:

(

0 CoreFoundation 0x95a1358a __raiseError + 410

1 libobjc.A.dylib 0x93460f49 objc_exception_throw + 56

2 CoreFoundation 0x95a5fa9b +[NSObject(NSObject) doesNotRecognizeSelector:] + 187

3 CoreFoundation 0x959bb026 ___forwarding___ + 950

4 CoreFoundation 0x959babf2 _CF_forwarding_prep_0 + 50

5 Swarm 0x000826bb +[Grid2d createBegin:] + 59

6 Swarm 0x00080b3c +[Discrete2d create:setSizeX:Y:] + 55

7 Swarm 0x0008267a +[Grid2d create:setSizeX:Y:] + 73

8 Heatbugs 0x00006e57 +[HeatbugsWorld createBegin:withModel:andSize:] + 55

9 Heatbugs 0x00003cf2 +[HeatbugsModel heatbugModelWithAZone:] + 338

10 Swarm 0x0001e726 +[CreateDrop_s create:] + 41

11 Heatbugs 0x00003221 -[HeatbugsGUI buildObjects] + 145

12 Swarm 0x000860e6 -[OpenStepSwarmController newSimulation:] + 211

13 Foundation 0x98c90964 -[NSThread main] + 45

14 Foundation 0x98c90914 __NSThread__main__ + 1499

15 libSystem.B.dylib 0x94800f39 _pthread_start + 345

16 libSystem.B.dylib 0x94800dbe thread_start + 34

)

1. Scott - based on what you said regarding zones - quite correctly - even a [HeatbugsWorld alloc] would crash - so I've removed all such methods and functions, but now I need to find a way of encapsulating swarm-framework implementation details from the user-app - mostly just to make sure that I can do it - and that I have a good understanding of how it all works.

2. I'm also a little confused with protocols and classes that share the same name - such as Grid2d - is that how things should be done? Is that good practice - should I be doing it? :)

I found this which explains protocol vs class names, so we can ignore question 2 :)....

3. Finally, notice that the [Grid2d create:setSizeX:Y:] takes no Zone info, could that be related to my problem? I did try [[Grid2d createBegin:z] ...] but had no luck there either.

4. Sorry for the unlimited supply of newb-spam.

Nima

From:	Nima Talebi
Subject:	[swarm-hackers] Re: Still learning the framework...
Date:	Tue, 17 Nov 2009 14:50:19 +1100