Re: #import is obsolete

[Richard Frith-Macdonald]

On Friday, July 4, 2003, at 08:25 PM, Andreas Hoeschler wrote:

> Hi,
>
> while building my MacOSX code on GNUstep (latest release) I get stuff 
> like
>
> 	Controller.m:2:2: warning: #import is obsolete, use an #ifndef 
> wrapper in the header file
>
> What is this about? Why is usage of #import discouraged?

The gist of the argument seems to be that it doesn't work reliably and 
can't be made to
work reliably (I don't know the technicalities).
In practice, the last I heard was that the maintainers of gcc intend to 
remove it, from
the compiler, and that various people at apple agreed with them.

> I would like to use the same source tree for MacOSX and GNUstep. Is 
> this a critical message or can it savely be ignored?

I don't think it's immediately critical (and as long as all your source 
resides on the same filesystem I don't think import will actually go 
wrong), but it seems likely to be critical in the long term ... the 
warning is intended to start you converting your code now rather than 
having it all break in a year or so, so you have to convert it all at 
once.

What you need to do is put code like this in all you headers ...

#ifndef SOME_UNIQUE_SYMBOL
#define SOME_UNIQUE_SYMBOL
// rest of header content
#endif