On Thursday, 27 March 2014 at 21:54:00 UTC, Andrei Alexandrescu
wrote:
On 3/27/14, 1:58 PM, Walter Bright wrote:
On 3/27/2014 12:50 PM, Andrei Alexandrescu wrote:
Yah, agreed. -- Andrei
Completely unworkable. To determine if a range is empty or
not, it may
have to actually read from its input. TTYs are an example.
Although
empty may then cache the result, and not read the second time
it is
called, an observer of TTY could see that an item was read
from the TTY.
That's a good point too.
Andrei
Yes, but the "observability" should be sort lived, since empty is
virtually guaranteed to be followed by "front" anyways. If both
front/empty do the same (lazy) operation on the stream, then
whether or not empty was called isn't really "observable" (to a
certain extent).
In contrast, having front completly fail if empty was NOT called,
means "empty" has a hell of a lot of observable side effect.
