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

[Andrei Alexandrescu]

On 7/10/12 11:03 AM, Timon Gehr wrote:
> On 07/10/2012 05:01 PM, Andrei Alexandrescu wrote:
>> On 7/10/12 10:32 AM, kenji hara wrote:
>>> OK. I know the past discussion about 'sealed container' so I can agree
>>> with your argument.
>>> Then I'll close the pull request.
>>
>> Sounds good for now but let's keep in mind the possibility of
>> restricting ref returns. At that point we can "open up" ref returns in
>> std.container.
>>
>> Andrei
>
> Would that apply to all ref returns or would there be an additional
> attribute that allows to explicitly restrict them?

If we decide to introduce the feature it would apply to all ref 
parameters and results. That means functions receiving a ref parameter 
cannot save its address anywhere, and that callers of functions that 
return a ref result cannot save the address beyond the function call.

Still trying to figure out whether this is too restrictive. My opinion 
is that that's sensible because many uses opposing it are antipatterns 
anyway. For example, if a function sneaks away the address of something 
it better makes that clear in the signature by requiring a pointer in 
the first place.


Andrei