How do you create a 'string'?

[twin lantern]

var value = try self.arena.alloc(u8, stuff.len);
@memcpy(value, stuff);

Zig complains that value is a local variable never mutated. So then I try this:

var value = try self.arena.alloc(u8, stuff.len);
@memcpy(&value, stuff);

But this too fails:

index.zig:47:25: error: type '*[]u8' is not an indexable pointer
              @memcpy(&value, stuff);

What is the correct way to create a longer lived 'string' from a buffer?

[orchid badge]

just make it const

memcpy is modifying the data that the slice is pointing to not the value of the slice itself

[twin lantern]

Oh, too easy, thanks!

[safe ocean]

@twin lantern is this some advanced usage that is specific to your unique situation, or just the default that you found when learning the lang?

asking because ArrayList(u8) and []const u8 are much cleaner for dealing with the typical string usecases, so just in case you are not aware of them

[twin lantern]

Thanks for asking, I am processing and loading a large data set into memory that lives for the lifetime of the program, it uses about 700mb right now in rust. I am assuming loading each slice into an arena like this is faster and more memory efficient than using array lists.

The current rust version can run on an iPhone, but iOS likes to kill it regularly

[hearty wing]

Hi. In general is ArrayList the go to structure for heap allocated strings? I'm coming from Rust and looking for a String replacement. A bit weird to have to do u8_array.items to get the actual content but no biggie.

[hidden quiver]

depends. do you wanna be able to resize and modify them? yes, use arraylist. do you just want static, immutable strings? just use a slice

[hearty wing]

I mainly want to "own" the data so that I can free it at an arbitrary time.

[hidden quiver]

just heap-allocate a slice then :)

[hearty wing]

I see. So just dupe(slice) and then free it with the same allocator type?

[hidden quiver]

yep

[hearty wing]

Sounds good thanks 🙂

[coarse coral]

Are you gonna store a lot of slices? Each slice takes 16 bytes to store pointer + length, so store a lot of them can be pretty memory inefficient

[safe nest]

Array list is good at building and formatting strings (through writer()), but you should use .toOwnedSlice() when you are done with it. Otherwise allocator interface has dupe for duping slices

[hearty wing]

Getting the hang of it. Will need to figure out how to go about passing allocators everywhere!