assumeSafeAppend on slice of static array?

[H. S. Teoh via Digitalmars-d]

On Tue, Apr 22, 2014 at 06:59:05PM +0000, monarch_dodra via Digitalmars-d wrote:
> On Tuesday, 22 April 2014 at 18:47:16 UTC, Dmitry Olshansky wrote:
> >22-Apr-2014 22:10, H. S. Teoh via Digitalmars-d пишет:
[...]
> >>The question is, is there a way to take a slice of the static array,
> >>set the length to zero, and append to it with ~= such that when it
> >>runs out of space in the static buffer, it will reallocate a longer
> >>array on the GC heap? Or is this a bad idea?
> >>
> >
> >Should be a canonical use case for ScopeBuffer
> >https://github.com/D-Programming-Language/phobos/blob/master/std/internal/scopebuffer.d
> >
> >Except that it has crippled usability e.g. you need to call free
> >manually.
> 
> I've been working on a "ScopedAppender" that is *bit* slower than
> ScopeBuffer, but can be used on any generic types, and is
> nothrow/ctfe/pure/"sometimes safe". I'm giving it the "finishing
> touches".
> 
> But in the meantime, normal appender+clear can work:
> 
> int[50] buf;
> auto app = appender(buf[]);
> app.clear();
> //app is ready for use.
> 
> The "issue" though is that appender itself as a reference type, so
> just declaring it allocates, which kind of gets in the way of setting
> up a local scratch space to begin with.

Yeah, I'm already using appender for the general case of n items; right
now I'm just trying to optimize for the very common case where there are
only 1 or two items in the list by eliminating GC allocations for that
case. The fact that appender allocates defeats the whole purpose. :-/


T

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