Full closures for D

[Reiner Pope]

Reiner Pope wrote:
> Craig Black wrote:
>>> It's not an optimal solution because the "does the function escape" 
>>> heuristic captures too many functions.
>>
>> You could let the programmer specify explicitly whether or not to make 
>> a function a closure or not, maybe with a key word or something.
>>
>>
> 
> I would have thought 'scope' would have some role in this. It currently 
> means 'allocate on the stack', and (is this implemented yet?) when used 
> as a storage class for function parameters, it is supposed to mean, "I 
> won't escape this variable". You could extend the "does the function 
> escape" heuristic to say, "the function escapes if it is assigned to a 
> non-scope variable, or is used as a non-scope argument."
> 
> This would behave correctly for what I believe is one of the major uses 
> of functions: sort/search/etc with a predicate. These things almost 
> never escape the predicate, so they can be written:
> 
> T find(T)(ref T[] array, scope bool delegate(T t) matches)
> {
>     ...
> }
> 
> 
>     -- Reiner

Oh, and

void foo()
{
     int n = ...;
     ...
     scope dg = { return n+2; };
     ...
}

gives you a way to tell the compiler, "dg doesn't need to be a lexical 
closure".


     -- Reiner