toString refactor in druntime

[Jonathan Marler via Digitalmars-d]

On Saturday, 1 November 2014 at 12:31:15 UTC, Dicebot wrote:
> On Saturday, 1 November 2014 at 07:02:03 UTC, Walter Bright 
> wrote:
>> On 10/30/2014 8:30 AM, Steven Schveighoffer wrote:
>>> This is a typical mechanism that Tango used -- pass in a ref 
>>> to a dynamic array
>>> referencing a stack buffer. If it needed to grow, just update 
>>> the length, and it
>>> moves to the heap. In most cases, the stack buffer is enough. 
>>> But the idea is to
>>> try and minimize the GC allocations, which are performance 
>>> killers on the
>>> current platforms.
>>
>> We keep solving the same problem over and over. 
>> std.internal.scopebuffer does this handily. It's what it was 
>> designed for - it works, it's fast, and it virtually 
>> eliminates the need for heap allocations. Best of all, it's an 
>> Output Range, meaning it fits in with the range design of 
>> Phobos.
>
> It is not the same thing as ref/out buffer argument. We have 
> been running ping-pong comments about it for a several times 
> now. All std.internal.scopebuffer does is reducing heap 
> allocation count at cost of stack consumption (and switching to 
> raw malloc for heap) - it does not change big-O estimate of 
> heap allocations unless it is used as a buffer argument - at 
> which point it is no better than plain array.

Sorry if this is a stupid question but what's being discussed 
here? Are we talking about passing a scope buffer to toString, or 
are we talking about the implementation of the toString function 
allocating it's own scope buffer?  API change or implementation 
notes or something else?  Thanks.