On Sunday, 26 February 2012 at 10:25:31 UTC, Jonathan M Davis
wrote:
The index bit is highly debatable, as the discussion on that
shows
(personally, I tend to favor leaving it as-is, because it's
useful that way),
but regardless making either an rvalue wouldn't make any sense,
because they
have to be variables that you can operate on in the loop. Doing
anything else
would seriously break the semantics of foreach. The question is
simply whether
they should be actual copies so that you don't end up with them
altering
anything outside of the loop unless you mark them as ref or if
the type itself
is a reference type. The element is pretty much its own copy
regardless,
unless you mark it as ref, whereas the situation with the index
is more
complicated (as the discussion on that shows).
- Jonathan M Davis
Why does making either an rvalue not make any sense?
foreach(<modifiers> var; agg)
var = 7;
Then if var is not ref, the compiler marks it as an rvalue and
gives an error if you try to modify or take the address of it.
It's pretty unlikely to happen, but it fixes the problem of
accidentally modifying a foreach index or variable. Just because
it's in a variable doesn't mean the compiler can't treat it as an
rvalue.
