On Tuesday, 13 May 2014 at 11:04:18 UTC, Nordlöw wrote:
but I believe it would be better to let the (D) compiler
optimization stage figure out _automatically_ if it needs to
make a copy of the variable `numbers` or not depending on
whether `numbers` is used or not further down the body of
I'm surprised that nobody has answered this discussion...
Isn't this an important question/possibility now that we soon
have inference of uniqueness/immutability in DMD from Walters
work?
Ping!
In general, anything that involves optimization must by
definition not change program behavior. Copying vs. not copying
usually has visible consequences, and therefore cannot be decided
by the optimizer.
Furthermore, I think it is too fragile to (silently) base a
decision about copying on what happens further down the program.
You could too easily change something by accident.
The uniqueness changes in DMD are different, although I believe
they are not yet properly documented. Uniqueness is only decided
from the the expression that produced the value, but not from
what further happens with the value.
