Tricky semantics of ranges & potentially numerous Phobos bugs

[deadalnix]

Le 16/10/2012 17:17, H. S. Teoh a écrit :
> On Tue, Oct 16, 2012 at 05:01:57PM +0200, Tommi wrote:
>> On Tuesday, 16 October 2012 at 05:49:11 UTC, Jonathan M Davis wrote:
>>> So, I don't really know what the right answer is, but I _really_
>>> don't like the idea of having to worry about the result of front
>>> changing after a call to popFront in every single function that ever
>>> uses front.
>>
>> Isn't the deeper underlying problem here the fact that there's no
>> generic way to make a deep copy in this language (does any language?)
>> Making a deep copy of front would be a clean solution. I don't know
>> how to implement this generic deep copying functionality though. For
>> example: what would be the semantics of deep-copying a range?
>
> I don't think the problem here is whether we have a deep copy or not,
> but that the semantics of ranges are not defined clearly enough. If we
> clearly state, for example, that whatever is returned by .front must
> persist beyond popFront(), then it would be up to the range to implement
> the deep copy, e.g., return the .dup or .idup'd array instead of a
> reference to an internal buffer.
>

It wouldn't be enough. Does several call to front recompute things ? See 
http://d.puremagic.com/issues/show_bug.cgi?id=8803