Re: Warnings that won't go away
Re: Warnings that won't go away
- Subject: Re: Warnings that won't go away
- From: Sherm Pendley <email@hidden>
- Date: Wed, 30 Nov 2005 12:02:49 -0500
On Nov 30, 2005, at 8:07 AM, Tom Jones wrote:
What's the difference between
the @class directive and the #import directive...when should I use one
and not the other? I was using @class, and getting warnings. Do I need
to use #import when I am calling specific methods of my class, and use
@class when I want to instantiate a member variable of a particular
class?
That's basically it. @class tells the compiler that the named class
exists, but nothing else about it. It doesn't tell the compiler about
the class' methods.
One common usage is to use @class in header files. When you're
declaring instance variables, arguments, and return types, knowing
that a class exists is sufficient. Then, in your .m file, you'd use
#import to get the full definition of the class, so that you can call
its methods.
This helps to minimize dependencies and keep build times to a
minimum. If you #import Playlist.h in Song.h, then any file that
#imports Song.h will also depend on Playlist.h, and will need to be
recompiled if Playlist.h is edited. But, if you use @class in Song.h,
then Song.h will no longer depend on Playlist.h - and neither will
the files that #import Song.h.
sherm--
Cocoa programming in Perl: http://camelbones.sourceforge.net
Hire me! My resume: http://www.dot-app.org
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Cocoa-dev mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden