General Category > Ideas

Built-in managed pointers

(1/1)

lerno:
Taking a hint from Cyclone, Rust etc one could consider managed pointers / objects. There are several possibilities:

1. Introduce something akin to move/borrow syntax with a special pointer type, eg. Foo@ x vs Foo* y and make the code track Foo@ to have unique ownership.
2. Introduce ref-counted objects with ref-counted pointers. Again use Foo@ x vs Foo* y with the latter being unretained. This should be internal refcounting to avoid any of the issues going from retained -> unretained that shared_ptr has. Consequently any struct that is RC:ed needs to be explicitly declared as such.
3. Managed pointers: you alloc and the pointer gets a unique address that will always be invalid after use. Any overflows will be detected, but use of managed pointers is slower due to redirect and check.

Sample code for (2)

--- Code: ---type Foo struct @(refcounted) {
   i32 a;
}

func Bar(Foo@ a)
{
    printf("%d\n", sizeof(Foo)); // prints 8 due to RC
    printf("%d\n", rc(a)); // prints 1
    Foo@ x = a;
    printf("%d\n", rc(a)); // prints 2
    x = nil;
    printf("%d\n", rc(a)); // prints 1
    Foo* y = a;
    printf("%d\n", rc(a)); // prints 1
    Foo* z = malloc(sizeof(Foo)); // Not recommended!
    // TOOD discuss how to properly initialize a RC:ed variable.
}

--- End code ---

bas:
Managed pointers are part of the core design of a language. Rust for example was built around some
management ideas. In those languages you cannot do without something like this. I don't see how
introducing an ideas like this wouldn't alter a C-like language completely.

I think programming in C requires some skill and experience, but like handling a chainsaw. :)
I prefer cutting a tree with a chainsaw (never actually tried though) than with a plastic toy.. (Not comparing
Rust with a toy!). Once you have some experience in C, memory management is not that hard.

lerno:
Rust is very high maintenance in regards to memory management, but I think we should look for a small effort that can take us maybe 70% of the way.

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