On Monday, 17 June 2013 at 22:29:34 UTC, Joseph Rushton Wakeling
wrote:
On 06/17/2013 11:18 PM, Joseph Rushton Wakeling wrote:
A random range should be viewed (IMO) as nothing more than a
range that "was"
(conceptually) simply filled with random numbers. Calling
front on the same
range twice in a row *should* produce the same result: No
call to popFront => no
change to the range. If it did change, it'd be a blatant
violation of the range
concept. It also means you can't have safe/nothrow/pure/const
"front".
Completely agree, and I don't think this is in contradiction
with what I've
proposed. My proposed "rule" might be better stated to
clarify this.
Perhaps this would be a better statement:
************************************************************************
* Iterating fully over a given random range should produce
a different *
* sequence for each such complete iteration.
*
************************************************************************
I'm not sure what that means but...
So, if you do,
SomeRandomRange r;
x = r.front;
y = r.front;
assert(x == y); // Passes!!
But
SomeRandomRange r;
arr1 = array(r);
arr2 = array(r);
assert(x != y); // the two arrays are filled with
different sequences.
With reference ranges, that is indeed what you'd get.
I could even add:
SomeRandomForwardRange r;
auto arr1 = array(r.save);
auto arr2 = array(r);
assert(x == y); // This time both are the same
