On Sun, Nov 04, 2012 at 07:47:49PM -0800, Jonathan M Davis wrote:
[...]
> But in either case, all of the range types have to take it into
> account, complicating their implementations that much further, and
> fastRange would complicate those implementations far more than
> isTransient would, because it would require code duplication rather
> than just statically disallowing the transient range when it wouldn't
> work.
[...]
No code duplication is actually necessary, even when the range is
transient-capable. For example:
// New version of byLine
struct ByLine {
char[] buffer;
@property bool empty() {
...
}
@property char[] front() {
// NOTE: non-transient by default
return buffer.dup;
}
void popFront() {
...
}
auto transient() {
struct TransientByLine {
ByLine innerRange;
// This is the only code that needs to
// be "duplicated". Because it's
// actually different!
@property char[] front() {
return innerRange.buffer;
}
// empty, popFront, etc., just "inherit"
// from the inner range. No code
// duplication needed.
alias innerRange this;
}
return TransientByLine(this);
}
}
T
--
Tech-savvy: euphemism for nerdy.
