//  Animals.m   Copyright (c) Kari Laitinen

//  http://www.naturalprogramming.com

//  2013-06-09  File created.
//  2013-06-09  Last modification.


/*  This program demonstrates:
      - a simple Objective-C class
      - having a 'copy constructor' in a class
      - using NSString objects and converting them to C-style strings
      - using the 'automatic memory management' of Objective-C
*/


#include  <stdio.h>
#import <Foundation/Foundation.h>

@interface Animal : NSObject
{
   NSString* species_name ;
   NSString* stomach_contents ;
}

- (id) init: (NSString*) given_species_name ;
- (id) init_with_animal: (Animal*) another_animal  ;

- (NSString*) species_name ;      // These two getters are needed by
- (NSString*) stomach_contents ;  // the 'copy constructor'

- (void) feed: (NSString*) food_for_this_animal ;
- (void) make_speak ;
   
@end

@implementation Animal

- (id) init: (NSString*) given_species_name 
{
   self = [ super init ] ;
   
   if ( self )
   {
      species_name =
            [ [ NSString alloc ] initWithString: given_species_name ] ;
      
      stomach_contents = 
            [ [ NSString alloc ] initWithString: @"" ] ;
   }
   
   return self ;
}


- (id) init_with_animal: (Animal*) another_animal 
{
   self = [ super init ] ;
   
   if ( self )
   {
      species_name = [ another_animal species_name ] ;
      
      stomach_contents = [ another_animal stomach_contents ] ;
   }
   
   return self ;
}

- (NSString*) species_name
{
   return species_name ;
}

- (NSString*) stomach_contents 
{
   return stomach_contents ;
}


- (void) feed: (NSString*) food_for_this_animal 
{
   // A new NSString object is created by this method.
   // I suppose the memory for the old object is freed automatically.

   stomach_contents =
   
      [ NSString stringWithFormat: @"%@ %@,", stomach_contents,
                                              food_for_this_animal ] ;
}

- (void) make_speak
{
   NSString* text_to_print =
     [ NSString stringWithFormat: 
        @"\n Hello, I am a %@. \n I have eaten %@ \n", 
           species_name, stomach_contents ] ;
           
   // The following statement converts a NSString to a
   // C-style string. According to documentation, the memory
   // of the C-style string will be automatically freed.
   printf( "%s", [ text_to_print UTF8String ] ) ;
}


@end


int main( void )
{
   NSAutoreleasePool* autorelease_pool = [ [ NSAutoreleasePool alloc ] init ] ;
     
   Animal*  cat_object = [ [ Animal alloc ] init: @"cat" ] ;
   Animal*  dog_object = [ [ Animal alloc ] init: @"vegetarian dog" ] ;

   [ cat_object feed: @"fish" ] ;
   [ cat_object feed: @"chicken" ] ;

   [ dog_object feed: @"salad" ] ;
   [ dog_object feed: @"potatoes" ] ;



   Animal*  another_cat = [ [ Animal alloc ] init_with_animal: cat_object ] ;
   
   [ another_cat feed: @"milk" ] ;

   [ cat_object make_speak ] ;
   [ dog_object make_speak ] ;
   [ another_cat make_speak ] ;

   [ autorelease_pool drain ] ;
}

/* NOTES:

   Useful links:
   http://stackoverflow.com/questions/2216266/printing-an-nsstring
   
   http://mobile.tutsplus.com/tutorials/iphone/learn-objective-c-day-5/
   
   
   It seems that when the autorelease pool is in use, it is not good to
   try to release objects programmatically.
   
   This program can be compiled and run with commands such as:
   
      gcc Animals.m -o a.out -framework Foundation
      ./a.out
   
*/