Objective-c compiling issues... help?

Please forgive me since this question i am also sure, has been asked before i expect. The problem i am having is that i am trying to learn obj-c on a pc seeing as i do not have a mac yet. i am using Jedit to write my code and GNUstep to compile and create. however my problem is occurring when trying to compile using the #include

according to the book i am using to learn as well as everything else i have found online (and do not quite understand), i need either a make file or point my compiler at a library or directory. i would prefer the make file i suppose as it seems a lot easier and faster to test things and learn.

the main question then is this: i seem to have found a GNUmake file that came with the online additions to my book, but i do not know how to use it or where to go with it. so if some one can please point out for me a easy to understand process or knows开发者_开发知识库 of such process and would be willing to impart that wisdom, it would be much appreciated.

Thank you kindly for your time

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Assuming you have installed GNUstep correctly and your environment is set up (all explained in the documentation) then you actually need to create a blank GNUmakefile in the root directory of your project and list your sources in that.

Here's a simple "Hello World" command line example:

Create a directory to contain your source code. HelloWorld would be a good idea.

In that, create files main.m, Greeter.m and Greeter.h.

We'll create the Greeter class which will just have one method -sayHelloToRecipient:.

In the Greeter.h:

#import <Foundation/Foundation.h>

@interface Greeter : NSObject {
}

-(void)sayHelloToRecipient:(NSString *)recipientName;

@end

And in the Greeter.m:

#import "Greeter.h"

@implementation Greeter

-(void)sayHelloToRecipient:(NSString *)recipientName {
    NSLog(@"Hello %@!", recipientName);
}

@end

Your main.m file simply includes the Greeter and invokes it with the argument @"World".

#import "Greeter.h"

int main(void) {
    Greeter *greeter = [[Greeter alloc] init];
    [greeter sayHelloToRecipient:@"World"];
    [greeter release];
    return 0;
}

Now you've got your sources ready to build, you just need to create a GNUmakefile. Make an empty file, and start it with the line: include $(GNUSTEP_MAKEFILES)/common.make, ending with the line include $(GNUSTPEP_MAKEFILES)/tool.make.

The first line includes all the other makefiles and targets GNUstep provides. The last line includes the makefiles needed to produce a command line tool. If you were build a GUI app you'd include application.make. For frameworks you'd include framework.make etc.

include $(GNUSTEP_MAKEFILES)/common.make

# Your project-specific directives will go here

include $(GNUSTEP_MAKEFILES)/tool.make

The stuff you put between these lines is the stuff that changes from project to project.

The complete GNUmakefile looks like this:

include $(GNUSTEP_MAKEFILES)/common.make

HELLO_ROOT_DIR = $(abspath .)

GNUSTEP_BUILD_DIR = $(HELLO_ROOT_DIR)/build

TOOL_NAME = HelloWorld

HelloWorld_OBJC_FILES = \
    Greeter.m \
    main.m

include $(GNUSTEP_MAKEFILES)/tool.make

HELLO_ROOT_DIR is entirely optional and is just a variable that saves me from having to re-type the path to the root as the project grows (and so does the complexity of the makefile).

TOOL_NAME is required for a command line tool and specifies both the output filename, and determines what you need to use for the *_OBJC_FILES line (i.e. in this case I need to use HelloWorld_OBJC_FILES because TOOL_NAME is "HelloWorld".

With this in place, provided you're in the same directory as the makefile, you should be able to just type `make' to build the tool. It will create a "build" directory and inside that you'll find the executable. This one when invoked just outputs:

-$  ./build/obj/HelloWorld 
2010-11-28 03:36:28.459 HelloWorld[12949] Hello World!

None of this will work however if your environment is not configured correctly. I've never done this on Windows, but I assume the same principles apply. That's running a shell script on Linux/UNIX (running batch file on Windows?) in order to configure the environment.

-$  . /usr/share/GNUstep/Makefiles/GNUstep.sh

You can check if it's correctly configured by printing the environment variable GNUSTEP_MAKEFILES to the console:

-$  echo $GNUSTEP_MAKEFILES

(Not sure how you do this on Windows)

If it outputs nothing, your environment is not correctly configured and/or GNUstep is not correctly installed. If it outputs a path, you should be safe to run `make'.