Is this range behaviour correct?

[monarch_dodra]

On Thursday, 14 March 2013 at 13:20:51 UTC, Andrea Fontana wrote:
> On Thursday, 14 March 2013 at 12:29:26 UTC, Andrei Alexandrescu 
> wrote:
>> On 3/14/13 6:45 AM, Andrea Fontana wrote:
>>> On Thursday, 14 March 2013 at 10:08:53 UTC, Andrea Fontana 
>>> wrote:
>>>> I'm trying to implement a db cursor as simple InputRange. I 
>>>> can't
>>>> implement as forward range because using c-api I can't 
>>>> clone/save cursor.
>> Add .save() to it.
>>
>> Andrei
>
> I can't add save and create a forward range: c-api doesn't 
> allow me to clone db cursor.

But think about it. You say you can't save, but you want pass by 
value to preserve state. If you can preserve state, doesn't that 
mean you just saved?

Once you've passed your "can't preserve state" to a foreach, then 
your range is consumed. So yes, it is correct behavior.

Most input ranges should model reference semantics when 
passed/copied by value. If somebody modifies the range, all 
ranges are affected. The tough part is usually preserving correct 
state.