A few thoughts on std.allocator

[Panke via Digitalmars-d]

On Sunday, 10 May 2015 at 10:51:54 UTC, Michel Fortin wrote:
> On 2015-05-10 09:50:00 +0000, Andrei Alexandrescu 
> <SeeWebsiteForEmail at erdani.org> said:
>
>> 3. Thread-local vs. shared objects
>> 
>> Currently in D it's legal to allocate memory in one thread and 
>> deallocate it in another. (One simple way to look at it is 
>> casting to shared.) This has a large performance cost that 
>> only benefits very few actual cases.
>> 
>> It follows that we need to change the notion that you first 
>> allocate memory and then brand it as shared. The "will be 
>> shared" knowledge must be present during allocation, and use 
>> different methods of allocation for the two cases.
>
> Shared is implicit in the case of immutable. Think carefully: 
> if you implement this and it has any efficiency benefit for 
> non-shared allocations, const-allocated objects and arrays will 
> become more performant than immutable-allocated ones. People 
> will thus have an incentive to stay away from immutable.

If immutable does not pull its weight in other ways, it's just 
not worth it.