> On Jul 14, 2020, at 2:38 PM, Simon Fraser <simon.fra...@apple.com> wrote:
>
> Could someone educate me about <wtf/Forward.h>? When should I use this
> instead of individual wtf headers?
Forward.h is analogous to forward-declaring a class ('class IntPoint;' instead
of ‘#include “IntPoint.h”'), but it works for many often-used classes and class
templates in the WTF namespace, including class templates that would be
difficult to correctly forward-declare due to their many arguments, such as
WTF::Vector. And it includes “using WTF::String” and the like, as well, to
import WTF namespace things into the global namespace.
We can use it any time we need a forward-declaration, not an entire definition,
of one of the items. For example, to compile a header that just takes and
returns String objects, we only need a forward declaration of String. The
easiest way to correctly do that is to include <wtf/Forward.h>. Including
<wtf/WTFString.h> pulls in a lot more. For the specific case of String, I think
you might be able to go further and write this instead:
namespace WTF {
class String;
}
using WTF::String;
But I have never tried it, and there might be some problem with that.
— Darin_______________________________________________
webkit-dev mailing list
webkit-dev@lists.webkit.org
https://lists.webkit.org/mailman/listinfo/webkit-dev
