On Tuesday, 16 October 2012 at 17:06:06 UTC, Jonathan M Davis
wrote:
There's also no way to validate that front always returns the
same value, or that popFront actually pops a value, or that it
pops only one value, etc. Pretty much _all_ that we can verify
with template constraints is function signatures. So, we can
_never_ fully restrict range types to exactly what would be
considered correct.
An option that may be decided on, is if an enum is used to
specify certain behavior decisions made by the programmer, then
only a few new templates to check for those and return true when
those are specifically true. Perhaps an example to use?
enum RangeTypes { normal, mutating, popDisgarded, ... }
template isRangeMutating(T)
if (hasMember!(T, "rangeType")) {
enum isRangeMutating = T.rangeType == RangeType.mutating;
}
//function that cannot accept input range that mutates any
members due to
//popFront/popBack
void something(I)(I input)
if (isInputRange!(I) && (!isRangeMutating!(I)))
{ /*...*/ }
