DIP1000: Scoped Pointers (Discussion)

[Andrei Alexandrescu via Digitalmars-d]

On 08/12/2016 04:58 PM, Timon Gehr wrote:
> On 12.08.2016 22:22, Andrei Alexandrescu wrote:
>> On 08/12/2016 03:34 PM, Timon Gehr wrote:
>>> On 10.08.2016 22:36, Dicebot wrote:
>>>> http://forum.dlang.org/post/pqsiqmkxenrwxoruzaml@forum.dlang.org
>>>>
>>>> The first DIP has just landed into the new queue. It is a proposal from
>>>> language authors and thus it bypasses usual nitpicking process and
>>>> proceeds straight to requesting community (your!) feedback.
>>>>
>>>> Essentially, it is an attempt to solve reference lifetime problem by
>>>> extending implementation of `scope` keyword.
>>>>
>>>> Proposal text:
>>>> https://github.com/dlang/DIPs/blob/master/DIPs/DIP1000.md
>>>
>>> This proposes to add a kind of information the type system is supposed
>>> to track (lifetimes), which cannot be communicated losslessly across
>>> function and aggregate boundaries. Hence it won't work well in its
>>> current form.
>>
>> Could it work in a restricted manner, yet permissive enough to be
>> useful? -- Andrei
>
> The issue is that there is information that the type system tracks that
> cannot be passed around effectively at the type system level.
>
> This generally leads to a painful "fighting-the-compiler" experience
> when trying to use the feature in a not-completely-trivial capacity
> (c.f. inout, it is also a case of this). I think users of the language
> generally expect features to compose. So even if it is useful for the
> handful of special cases it was designed for, there will be a lot of
> complaints.

Can you please give examples of cases that are (a) unlikely to be 
supported with reasonable effort, and (b) likely to cause problems in 
usability? Thanks! -- Andrei