Semantics of toString

[Steven Schveighoffer]

On Thu, 12 Nov 2009 08:22:26 -0500, Steven Schveighoffer  
<schveiguy at yahoo.com> wrote:

> On Tue, 10 Nov 2009 18:49:54 -0500, Andrei Alexandrescu  
> <SeeWebsiteForEmail at erdani.org> wrote:
>
>> I think the best option for toString is to take an output range and  
>> write to it. (The sink is a simplified range.)
>
> Bad idea...
>
> A range only makes sense as a struct, not an interface/object.  I'll  
> tell you why: performance.
>
> Ranges are special in two respects:
>
> 1. They are foreachable.  I think everyone agrees that calling 2  
> interface functions per loop iteration is much lower performing than  
> using opApply, which calls one delegate function per loop.  My  
> recommendation -- use opApply when dealing with polymorphism.  I don't  
> think there's a way around this.

Oops, I meant 3 virtual functions -- front, popNext, and empty.

-Steve