foreach ref very broken: fails to call front(val)

[kenji hara]

2012/7/10 Andrei Alexandrescu <SeeWebsiteForEmail at erdani.org>:
> On 7/10/12 4:29 AM, kenji hara wrote:
>>
>> Posted a pull request:
>> https://github.com/D-Programming-Language/phobos/pull/678
>
>
> Hmm, that has a couple of issues.
>
> First, map that modifies things in place is a bug more often than a feature
> given that the caller of map may use front() an arbitrary number of times.
> So I see little intentional and legitimate use for things like map!"a +=
> 2"(range).
>
> Second, the return by value from Array is intentional and has to do with
> sealing. Array is intended to never escape the addresses of its elements.
> That way, the collection is "sealed" in the sense there can never be
> uncontrolled pointers to its elements. This allows using efficient
> allocation strategies for the array without compromising its safety.
>
> In more recent discussions with Walter we discussed the possibility of
> making "ref" returns transitory, i.e. no caller code can actually save a ref
> result beyond the call. That would allow us to keep sealing while also
> benefitting of ref returns. But that feature has not been implemented yet.

OK. I know the past discussion about 'sealed container' so I can agree
with your argument.
Then I'll close the pull request.

Thanks.

Kenji Hara