Compiling objective-c programs without gnustep on ubuntu - objective-c

Question

is there any way to compile objective c programs on ubuntu without the use of GNUStep? I want to use the default C standard libraries and all but with Objective-C's OOB syntax. The problem I am having now is once I have all the methods up, I need a way to call them. In Mac I would just alloc and init it but on Linux when I try to compile this, clang just gives me an error.
#include <stdio.h> // C standard IO library (for printf)
#include <stdlib.h> // C standard library
// Interface
#interface test
-(void)sayHello :(char *)message;
#end
// Implementation
#implementation test
-(void)sayHello :(char *)message {
printf("%s", message);
}
int main(int argc, char *argv[]) {
test *test = [[test alloc] init];
[test sayHello:"Hello world"];
}

Answer 1

You can compile objective-c with gcc, but remember to use the -lobjc switch so the compiler knows what language you're using.
You'll also need to include the following header:
#import <objc/Object.h>
...and extend Object from your interface. See the hello world example for objective-c here:
http://en.m.wikipedia.org/wiki/List_of_Hello_world_program_examples#O

Answer 2

Good question - it got me to dig into the matters myself, since I want to rewrite several old Python projects in a normal language (C/ObjC), so I aim both to stay away from Crap++ and avoid GNUstep overhead. Here goes my try-and-test solution:
Foo.h:
#import <objc/Object.h>
#interface Foo: Object
{
#private
int
bar;
}
+ (id) alloc;
+ (id) new;
- (id) init;
- (id) set_bar: (int)value;
- (int) get_bar;
#end
Foo.m:
#import <stdio.h>
#import <objc/runtime.h>
#import "Foo.h"
#implementation Foo
+ (id) alloc
{
puts(__func__);
return class_createInstance(self, 0);
}
+ (id) new
{
return [[self alloc] init];
}
- (id) init
{
puts(__func__);
bar = 31;
return self;
}
- (id) set_bar: (int)value
{
puts(__func__);
bar = value;
return self;
}
- (int) get_bar
{
puts(__func__);
return bar;
}
#end
main.m:
#import <stdio.h>
#import "Foo.h"
int
main
()
{
id
foo = [Foo new];
printf("old bar: %i\n", [foo get_bar]);
[foo set_bar: 10];
printf("new bar: %i\n", [foo get_bar]);
return 0;
}
Makefile:
run: main.o Foo.o
gcc $^ -o $# -lobjc
main.o: main.m Foo.h
gcc -c $< -o $#
Foo.o: Foo.m Foo.h
gcc -c $< -o $#
The output I've got:
+[Foo alloc]
-[Foo init]
-[Foo get_bar]
old bar: 31
-[Foo set:bar:]
-[Foo get_bar]
new bar: 10
Looks like it works!