| ... | ... | @@ -6,28 +6,13 @@ const Point = struct { |
| 6 | 6 | y: f32, |
| 7 | 7 | }; |
| 8 | 8 | |
| 9 | | // Maybe we want to pass it to OpenGL so we want to be particular about |
| 10 | | // how the bytes are arranged. |
| 11 | | const Point2 = packed struct { |
| 12 | | x: f32, |
| 13 | | y: f32, |
| 14 | | }; |
| 15 | | |
| 16 | 9 | // Declare an instance of a struct. |
| 17 | | const p = Point{ |
| 10 | const p: Point = .{ |
| 18 | 11 | .x = 0.12, |
| 19 | 12 | .y = 0.34, |
| 20 | 13 | }; |
| 21 | 14 | |
| 22 | | // Maybe we're not ready to fill out some of the fields. |
| 23 | | var p2 = Point{ |
| 24 | | .x = 0.12, |
| 25 | | .y = undefined, |
| 26 | | }; |
| 27 | | |
| 28 | | // Structs can have methods |
| 29 | | // Struct methods are not special, they are only namespaced |
| 30 | | // functions that you can call with dot syntax. |
| 15 | // Functions in the struct's namespace can be called with dot syntax. |
| 31 | 16 | const Vec3 = struct { |
| 32 | 17 | x: f32, |
| 33 | 18 | y: f32, |
| ... | ... | @@ -46,7 +31,6 @@ const Vec3 = struct { |
| 46 | 31 | } |
| 47 | 32 | }; |
| 48 | 33 | |
| 49 | | const expect = @import("std").testing.expect; |
| 50 | 34 | test "dot product" { |
| 51 | 35 | const v1 = Vec3.init(1.0, 0.0, 0.0); |
| 52 | 36 | const v2 = Vec3.init(0.0, 1.0, 0.0); |
| ... | ... | @@ -67,14 +51,14 @@ test "struct namespaced variable" { |
| 67 | 51 | try expect(Empty.PI == 3.14); |
| 68 | 52 | try expect(@sizeOf(Empty) == 0); |
| 69 | 53 | |
| 70 | | // you can still instantiate an empty struct |
| 71 | | const does_nothing = Empty{}; |
| 54 | // Empty structs can be instantiated the same as usual. |
| 55 | const does_nothing: Empty = .{}; |
| 72 | 56 | |
| 73 | 57 | _ = does_nothing; |
| 74 | 58 | } |
| 75 | 59 | |
| 76 | | // struct field order is determined by the compiler for optimal performance. |
| 77 | | // however, you can still calculate a struct base pointer given a field pointer: |
| 60 | // Struct field order is determined by the compiler, however, a base pointer |
| 61 | // can be computed from a field pointer: |
| 78 | 62 | fn setYBasedOnX(x: *f32, y: f32) void { |
| 79 | 63 | const point: *Point = @fieldParentPtr("x", x); |
| 80 | 64 | point.y = y; |
| ... | ... | @@ -88,8 +72,7 @@ test "field parent pointer" { |
| 88 | 72 | try expect(point.y == 0.9); |
| 89 | 73 | } |
| 90 | 74 | |
| 91 | | // You can return a struct from a function. This is how we do generics |
| 92 | | // in Zig: |
| 75 | // Structs can be returned from functions. |
| 93 | 76 | fn LinkedList(comptime T: type) type { |
| 94 | 77 | return struct { |
| 95 | 78 | pub const Node = struct { |
| ... | ... | @@ -105,8 +88,7 @@ fn LinkedList(comptime T: type) type { |
| 105 | 88 | } |
| 106 | 89 | |
| 107 | 90 | test "linked list" { |
| 108 | | // Functions called at compile-time are memoized. This means you can |
| 109 | | // do this: |
| 91 | // Functions called at compile-time are memoized. |
| 110 | 92 | try expect(LinkedList(i32) == LinkedList(i32)); |
| 111 | 93 | |
| 112 | 94 | const list = LinkedList(i32){ |
| ... | ... | @@ -139,4 +121,6 @@ test "linked list" { |
| 139 | 121 | // instead of try expect(list2.first.?.*.data == 1234); |
| 140 | 122 | } |
| 141 | 123 | |
| 124 | const expect = @import("std").testing.expect; |
| 125 | |
| 142 | 126 | // test |
Andrew Kelley <andrew@ziglang.org> 2024-11-13 15:35:16-08:00
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