zig-arraylist

name	zig-arraylist
description	Reference for Zig 0.15+ ArrayList API which passes the allocator to each method call instead of at initialization. Use when working with ArrayLists in Zig 0.15+.

Zig 0.15 ArrayList API

This project uses Zig 0.15 which has a different ArrayList API than earlier versions.

Key Differences from Older Zig Versions

Initialization

Old (pre-0.15):

var list = std.ArrayList(T).init(allocator);

New (0.15+):

var list = std.ArrayList(T){};

The allocator is NOT passed at initialization. Instead, it's passed to each method call.

Common Operations

Append:

// Old
try list.append(item);

// New (0.15)
try list.append(allocator, item);

Deinit:

// Old
list.deinit();

// New (0.15)
list.deinit(allocator);

AppendSlice:

// Old
try list.appendSlice(items);

// New (0.15)
try list.appendSlice(allocator, items);

ToOwnedSlice:

// Old
const slice = try list.toOwnedSlice();

// New (0.15)
const slice = try list.toOwnedSlice(allocator);

Complete Example

const std = @import("std");

fn example(allocator: std.mem.Allocator) ![]u32 {
    // Initialize without allocator
    var list = std.ArrayList(u32){};
    defer list.deinit(allocator);

    // All operations take allocator as first arg
    try list.append(allocator, 1);
    try list.append(allocator, 2);
    try list.append(allocator, 3);

    // Convert to owned slice
    return try list.toOwnedSlice(allocator);
}

Why This Change?