memory management and the standard library

[Atila Neves]

On Saturday, 16 March 2019 at 21:17:02 UTC, Olivier FAURE wrote:
> On Saturday, 16 March 2019 at 20:17:50 UTC, Jacob Carlborg 
> wrote:
>> Instead of having a function allocate memory, pass a buffer, 
>> delegate, output range or something similar to the function. 
>> Then whatever you pass can decide if it should allocate using 
>> the GC, malloc or something else.
>
> It would have to be a delegate or an output range, because in 
> most cases the callee wouldn't know in advance how much storage 
> it needs to allocate.
>
> Anyway, it would be pretty nice if there were a standardized 
> way to tell a function how it should allocate its memory;

There is:

void fun(A)(auto ref A allocator);

> it would allow some nice strategies like "I know that I'm going 
> to discard most of what this function allocates, so just put in 
> in a continuous buffer; then deep-copy the relevant data to GC 
> memory, and throw the rest away" (eg in a parser).

This can all be done with a custom allocator, or one built with 
the building blocks in std.experimental.allocator.

>
> However, for that to work, you'd probably need a way to pass 
> implicit arguments to a function without having to specify 
> `foobar(defaultGcAllocator, x, y, z)` every time you call a 
> function.


void foobar(int x, int y, int z) {
     import std.experimental.allocator.gc_allocator: GCAllocator;
     foobar(GCAllocator.instance, x, y, z);
}

void foobar(A)(auto ref A allocator, int x, int y, int z) {
     // ...
}

Or use `theAllocator`.