Function scope arguments

[Artur Skawina]

On 01/15/13 15:09, Timon Gehr wrote:
> On 01/15/2013 01:44 PM, Artur Skawina wrote:
>> On 01/15/13 12:48, deadalnix wrote:
>>> On Tuesday, 15 January 2013 at 10:58:17 UTC, Artur Skawina wrote:
>>>> Different problem - lifetime. One approach would be to disallow escaping
>>>> them (which in this case includes returning them) unless the compiler is
>>>> able to do the right - ie the body of the function is available. Somewhat
>>>> unorthodox, but could work. (The problem are not the trivial cases; it's the
>>>> ones where the compiler has no idea which ref is escaped/returned at runtime)
>>>>
>>>
>>> The compiler should assume they may escape unless scope is specified.
>>
>> This is about /avoiding/ "hidden" heap allocations as much as possible. Having
>> functions with 'ref' and 'auto-ref' args always trigger them is not ideal.
>>
>> 'lazy' args are already problematic enough. (there's currently no way to mark
>> them as non-escaping, the compiler has to assume that the do -> the result is
>> that they /always/ cause heap allocations and you have to use explicit scoped
>> delegates instead, losing the syntax advantages)
> 
> Actually lazy args are implicitly 'scope' and never allocate.

I wish. :)

Seriously though, I don't.
They can be escaped and they do allocate. They have to. The problem is just
that there currently is no way to tell the compiler i-know-what-i'm-doing
and avoid the heap allocated closures.

[if the behavior changed in newer (than my old gdc) compiler versions then such a
change is bogus, as it would mean that stack objects could be escaped]

artur