mod(container): cleanup and highlight points for improvement

src/container.zig

@@ -566,6 +566,7 @@ pub fn Container(comptime Event: type) type {
         size: Point,
         properties: Properties,
         element: Element,
+        // TODO this should be renamed to `children`
         elements: std.ArrayList(@This()),
 
         /// Properties for each `Container` to configure their layout,
@@ -593,7 +594,7 @@ pub fn Container(comptime Event: type) type {
             };
         }
 
-        pub fn deinit(this: *@This()) void {
+        pub fn deinit(this: *const @This()) void {
             for (this.elements.items) |*element| {
                 element.deinit();
             }
@@ -855,7 +856,7 @@ pub fn Container(comptime Event: type) type {
             this.grow_resize(this.size);
         }
 
-        pub fn handle(this: *@This(), event: Event) !void {
+        pub fn handle(this: *const @This(), event: Event) !void {
             switch (event) {
                 .mouse => |mouse| if (mouse.in(this.origin, this.size)) {
                     // the element receives the mouse event with relative position
@@ -873,11 +874,12 @@ pub fn Container(comptime Event: type) type {
             }
         }
 
-        pub fn content(this: *const @This()) ![]const Cell {
+        pub fn content(this: *const @This()) ![]Cell {
             if (this.size.x == 0 or this.size.y == 0) return Error.TooSmall;
+
             const cells = try this.allocator.alloc(Cell, @as(usize, this.size.x) * @as(usize, this.size.y));
-            @memset(cells, .{});
             errdefer this.allocator.free(cells);
+            @memset(cells, .{});
 
             this.properties.layout.content(@This(), cells, this.origin, this.size, this.elements.items);
             this.properties.border.content(cells, this.size);

src/element.zig

@@ -182,6 +182,7 @@ pub fn Scrollable(Event: type) type {
         configuration: Configuration,
 
         pub const Configuration = packed struct {
+            // TODO the scrollbar bool and the color should be in their own struct using `enabled` and `color` inside of the struct to be more consistent with other `Configuration` structs
             scrollbar: bool,
             color: Color = .default,
             x_axis: bool = false,
@@ -281,7 +282,6 @@ pub fn Scrollable(Event: type) type {
             const size = container.size;
             const origin = container.origin;
             const contents = try container.content();
-            defer container.allocator.free(contents);
 
             const anchor = (@as(usize, origin.y) * @as(usize, container_size.x)) + @as(usize, origin.x);
 
@@ -294,6 +294,8 @@ pub fn Scrollable(Event: type) type {
                     if (contents.len == idx) break :blk;
                 }
             }
+            // free immediately
+            container.allocator.free(contents);
 
             for (container.elements.items) |child| try render_container(child, cells, size);
         }
@@ -306,13 +308,7 @@ pub fn Scrollable(Event: type) type {
             const offset_y: usize = if (this.configuration.y_axis) 1 else 0;
 
             const container_size = this.container.size;
-            const container_cells = try this.container.allocator.alloc(Cell, @as(usize, container_size.x) * @as(usize, container_size.y));
-            {
-                const container_cells_const = try this.container.content();
-                defer this.container.allocator.free(container_cells_const);
-                assert(container_cells_const.len == @as(usize, container_size.x) * @as(usize, container_size.y));
-                @memcpy(container_cells, container_cells_const);
-            }
+            const container_cells = try this.container.content();
 
             for (this.container.elements.items) |child| try render_container(child, container_cells, container_size);
 
@@ -705,7 +701,7 @@ pub fn Progress(Event: type, Queue: type) fn (meta.FieldEnum(Event)) type {
                 }
 
                 fn handle(ctx: *anyopaque, event: Event) !void {
-                    var this: *@This() = @ptrCast(@alignCast(ctx));
+                    const this: *@This() = @ptrCast(@alignCast(ctx));
                     // TODO should this `Element` trigger a completion event? (I don't think that this is useful?)
                     switch (event) {
                         progress_event => |value| {