Re: how to compile a .m

[David Chisnall]

A couple of other people have already mentioned GNUstep Make.  For  
short programs, gnustep-config is also an option.  You can compile a  
simple Objective-C program like this:

gcc `gnustep-config --objc-flags --base-libs` hello.m

This will generate an a.out file linked against GNUstep Base  
(Foundation).  Substitute --gui-libs if you want to link AppKit (but,  
generally, if you are linking against AppKit you will want to make a  
bundle and then it's much easier to use GNUstep Make).   For both, you  
will need to source the GNUstep.sh file first, I believe (I'm not 100%  
sure if gnustep-config needs this).

On 14 Oct 2009, at 00:30, Jean-Loïc Mauduy wrote:

> #import <stdio.h>


This is wrong.  A few Objective-C tutorials make this mistake, and  
tell you to just use #import instead of #include in Objective-C  
programs, but this is terrible advice.  #include is a trivial  
preprocessor directive that just inserts the contents of the specified  
file at this point.  #import is a bit more clever, and ensures that  
the file is only ever inserted once.

Objective-C headers are, generally, designed to be used with #import.   
A lot of C (and C++) headers, however, are not.  They will protect  
themselves from multiple inclusion with macros and may be designed to  
work differently if included more than once in a compilation unit.  If  
you get into the habit of using #import with C headers, then you are  
going to end up with something breaking eventually, and you are going  
to be very confused about why.  Only use #import with Objective-C  
headers; stick with #include for C headers.  This also provides a clue  
to people reading your code about what kind of header you are including.

David

-- Sent from my Apple II