Merge pull request 'Improve command line style' (#451) from manliop/exercises:improve-command-line-style into main

Reviewed-on: https://codeberg.org/ziglings/exercises/pulls/451

README.md

@@ -44,7 +44,7 @@ in that case, you can download it directly from the [build directory](https://zi
 Verify the installation and build number of `zig` like so:
 
 ```
-$ zig version
+zig version
 0.17.0-dev.xxxx+xxxxxxxxx
 ```
 

exercises/065_builtins2.zig

@@ -93,36 +93,25 @@ pub fn main() void {
 
     print("He has room in his heart for:", .{});
 
-    // A StructFields array
-    const fields = @typeInfo(Narcissus).@"struct".fields;
+    // `field_names` is a slice of strings and it holds the names of the struct's fields
+    // `field_types` is a slice of strings and it holds the types of the struct's fields,
+    //               it is guaranteed to be the same length as `field_names`
+    const field_names = @typeInfo(Narcissus).@"struct".field_names;
+    const field_types = @typeInfo(Narcissus).@"struct".field_types;
 
-    // 'fields' is a slice of StructFields. Here's the declaration:
-    //
-    //     pub const StructField = struct {
-    //         name: [:0]const u8,      // Don't worry about `:0` yet!
-    //         type: type,
-    //         default_value_ptr: ?*const anyopaque,
-    //         is_comptime: bool,
-    //         alignment: comptime_int,
-    //
-    //         defaultValue() ?sf.type  // Function that loads the
-    //                                  // field's default value from
-    //                                  // `default_value_ptr`
-    //     };
-    //
     // Please complete these 'if' statements so that the field
     // name will not be printed if the field is of type 'void'
     // (which is a zero-bit type that takes up no space at all!):
-    if (fields[0].??? != void) {
-        print(" {s}", .{fields[0].name});
+    if (field_???[???] != void) {
+        print(" {s}", .{field_???[???]});
     }
 
-    if (fields[1].??? != void) {
-        print(" {s}", .{fields[1].name});
+    if (field_???[???] != void) {
+        print(" {s}", .{field_???[???]});
     }
 
-    if (fields[2].??? != void) {
-        print(" {s}", .{fields[2].name});
+    if (field_???[???] != void) {
+        print(" {s}", .{field_???[???]});
     }
 
     // Yuck, look at all that repeated code above! I don't know

exercises/071_comptime6.zig

@@ -36,13 +36,14 @@ pub fn main() void {
     // statement was repeated three times almost verbatim. Yuck!
     //
     // Please use an 'inline for' to implement the block below
-    // for each field in the slice 'fields'!
+    // for each field in the corresponding slices (they're of the same length)!
 
-    const fields = @typeInfo(Narcissus).@"struct".fields;
+    const field_names = @typeInfo(Narcissus).@"struct".field_names;
+    const field_types = @typeInfo(Narcissus).@"struct".field_types;
 
     ??? {
-        if (field.type != void) {
-            print(" {s}", .{field.name});
+        if (field_type != void) {
+            print(" {s}", .{field_name});
         }
     }
 

exercises/082_anonymous_structs3.zig

@@ -74,36 +74,27 @@ fn printTuple(tuple: anytype) void {
     //     @typeInfo() - takes a type, returns a TypeInfo union
     //                   with fields specific to that type.
     //
-    //     The list of a struct type's fields can be found in
-    //     TypeInfo's @"struct".fields.
+    //     The list of a struct type's field types can be found in
+    //     TypeInfo's @"struct".field_types.
     //
     //     Example:
     //
-    //         @typeInfo(Circle).@"struct".fields
+    //         @typeInfo(Circle).@"struct".field_types
     //
-    // This will be an array of StructFields.
-    const fields = ???;
+    // This will be an array of field types.
+    const field_types = ???;
+
+    // This will be an array of field names.
+    const field_names = ???;
 
     // 2. Loop through each field. This must be done at compile
     // time.
     //
     //     Hint: remember 'inline' loops?
     //
-    for (fields) |field| {
+    for (???, ???) |???, ???| {
         // 3. Print the field's name, type, and value.
         //
-        //     Each 'field' in this loop is one of these:
-        //
-        //         pub const StructField = struct {
-        //             name: [:0]const u8,
-        //             type: type,
-        //             default_value_ptr: ?*const anyopaque,
-        //             is_comptime: bool,
-        //             alignment: comptime_int,
-        //         };
-        //
-        //     Note we will learn about 'anyopaque' type later
-        //
         //     You'll need this builtin:
         //
         //         @field(lhs: anytype, comptime field_name: []const u8)
@@ -123,8 +114,8 @@ fn printTuple(tuple: anytype) void {
         // for declarations. If it's a value, it looks for data.
         //
         print("\"{s}\"({any}):{any} ", .{
-            field.???,
-            field.???,
+            field_name,
+            field_type,
             ???,
         });
     }

patches/patches/065_builtins2.patch

@@ -1,5 +1,5 @@
---- exercises/065_builtins2.zig	2026-02-27 13:10:36
-+++ answers/065_builtins2.zig	2026-02-27 13:10:52
+--- exercises/065_builtins2.zig	2026-06-01 15:33:16.617432671 +0200
++++ answers/065_builtins2.zig	2026-06-01 15:33:31.104018108 +0200
 @@ -58,7 +58,7 @@
      // Oops! We cannot leave the 'me' and 'myself' fields
      // undefined. Please set them here:
@@ -18,22 +18,26 @@
  
      // Now we print a pithy statement about Narcissus.
      print("A {s} loves all {s}es. ", .{
-@@ -113,15 +113,15 @@
+@@ -102,16 +102,16 @@
      // Please complete these 'if' statements so that the field
      // name will not be printed if the field is of type 'void'
      // (which is a zero-bit type that takes up no space at all!):
--    if (fields[0].??? != void) {
-+    if (fields[0].type != void) {
-         print(" {s}", .{fields[0].name});
+-    if (field_???[???] != void) {
+-        print(" {s}", .{field_???[???]});
++    if (field_types[0] != void) {
++        print(" {s}", .{field_names[0]});
      }
  
--    if (fields[1].??? != void) {
-+    if (fields[1].type != void) {
-         print(" {s}", .{fields[1].name});
+-    if (field_???[???] != void) {
+-        print(" {s}", .{field_???[???]});
++    if (field_types[1] != void) {
++        print(" {s}", .{field_names[1]});
      }
  
--    if (fields[2].??? != void) {
-+    if (fields[2].type != void) {
-         print(" {s}", .{fields[2].name});
+-    if (field_???[???] != void) {
+-        print(" {s}", .{field_???[???]});
++    if (field_types[2] != void) {
++        print(" {s}", .{field_names[2]});
      }
  
+     // Yuck, look at all that repeated code above! I don't know

patches/patches/071_comptime6.patch

@@ -1,11 +1,11 @@
---- exercises/071_comptime6.zig	2024-09-02 19:21:50.250454978 +0200
-+++ answers/071_comptime6.zig	2024-09-02 19:21:23.553250563 +0200
-@@ -40,7 +40,7 @@
- 
-     const fields = @typeInfo(Narcissus).@"struct".fields;
+--- exercises/071_comptime6.zig	2026-06-01 15:35:27.223400223 +0200
++++ answers/071_comptime6.zig	2026-06-01 15:36:35.349728561 +0200
+@@ -41,7 +41,7 @@
+     const field_names = @typeInfo(Narcissus).@"struct".field_names;
+     const field_types = @typeInfo(Narcissus).@"struct".field_types;
  
 -    ??? {
-+    inline for (fields) |field| {
-         if (field.type != void) {
-             print(" {s}", .{field.name});
++    inline for (field_names, field_types) |field_name, field_type| {
+         if (field_type != void) {
+             print(" {s}", .{field_name});
          }

patches/patches/082_anonymous_structs3.patch

@@ -1,32 +1,32 @@
---- exercises/082_anonymous_structs3.zig	2026-02-27 13:05:46
-+++ answers/082_anonymous_structs3.zig	2026-02-27 13:07:22
-@@ -82,14 +82,14 @@
-     //         @typeInfo(Circle).@"struct".fields
+--- exercises/082_anonymous_structs3.zig	2026-06-01 15:59:11.872467805 +0200
++++ answers/082_anonymous_structs3.zig	2026-06-01 15:58:38.004730144 +0200
+@@ -82,17 +82,17 @@
+     //         @typeInfo(Circle).@"struct".field_types
      //
-     // This will be an array of StructFields.
--    const fields = ???;
-+    const fields = @typeInfo(@TypeOf(tuple)).@"struct".fields;
+     // This will be an array of field types.
+-    const field_types = ???;
++    const field_types = @typeInfo(@TypeOf(tuple)).@"struct".field_types;
+ 
+     // This will be an array of field names.
+-    const field_names = ???;
++    const field_names = @typeInfo(@TypeOf(tuple)).@"struct".field_names;
  
      // 2. Loop through each field. This must be done at compile
      // time.
      //
      //     Hint: remember 'inline' loops?
      //
--    for (fields) |field| {
-+    inline for (fields) |field| {
+-    for (???, ???) |???, ???| {
++    inline for (field_types, field_names) |field_type, field_name| {
          // 3. Print the field's name, type, and value.
          //
-         //     Each 'field' in this loop is one of these:
-@@ -123,9 +123,9 @@
-         // for declarations. If it's a value, it looks for data.
-         //
+         //     You'll need this builtin:
+@@ -116,7 +116,7 @@
          print("\"{s}\"({any}):{any} ", .{
--            field.???,
--            field.???,
+             field_name,
+             field_type,
 -            ???,
-+            field.name,
-+            field.type,
-+            @field(tuple, field.name),
++            @field(tuple, field_name),
          });
      }
  }

rivendell/elrond.zig

@@ -21,6 +21,7 @@ const builtin = @import("builtin");
 
 const Process = std.process;
 const print = std.debug.print;
+const cutPrefix = std.mem.cutPrefix;
 
 const progress_filename = ".progress.txt";
 
@@ -102,6 +103,16 @@ pub const Exercise = struct {
     }
 };
 
+// Shared, read-only run context threaded through the helpers.
+const Context = struct {
+    io: std.Io,
+    arena: std.mem.Allocator,
+    zig_exe: []const u8,
+    work_path: []const u8,
+};
+
+const Error = error{Failed};
+
 // Ansi colors.
 var use_color_escapes = false;
 var red_text: []const u8 = "";
@@ -138,7 +149,8 @@ pub fn main(init: std.process.Init) !void {
     const io = init.io;
     const arena = init.arena.allocator();
 
-    const args = try init.minimal.args.toSlice(arena);
+    var args_it = try init.minimal.args.iterateAllocator(arena);
+    if (!args_it.skip()) @panic("expected self arg");
 
     setupColors(io);
 
@@ -150,22 +162,21 @@ pub fn main(init: std.process.Init) !void {
     var only_n: ?usize = null;
     var start_n: ?usize = null;
 
-    for (1..args.len) |n| {
-        const arg = args[n];
+    while (args_it.next()) |arg| {
         if (std.mem.eql(u8, arg, "--logo")) {
             print("{s}{s}{s}", .{ yellow_text, logo, reset_text });
             return;
-        } else if (prefix(arg, "--zig=")) |v| {
+        } else if (cutPrefix(u8, arg, "--zig=")) |v| {
             zig_exe = v;
-        } else if (prefix(arg, "--work-path=")) |v| {
+        } else if (cutPrefix(u8, arg, "--work-path=")) |v| {
             work_path = v;
-        } else if (prefix(arg, "--only=")) |v| {
+        } else if (cutPrefix(u8, arg, "--only=")) |v| {
             only_n = std.fmt.parseInt(usize, v, 10) catch {
                 print("invalid --only value: {s}\n", .{v});
                 std.process.exit(1);
             };
             mode = .named;
-        } else if (prefix(arg, "--start=")) |v| {
+        } else if (cutPrefix(u8, arg, "--start=")) |v| {
             start_n = std.fmt.parseInt(usize, v, 10) catch {
                 print("invalid --start value: {s}\n", .{v});
                 std.process.exit(1);
@@ -181,7 +192,12 @@ pub fn main(init: std.process.Init) !void {
 
     print("{s}", .{logo});
 
-    const ctx: Context = .{ .io = io, .arena = arena, .zig_exe = zig_exe, .work_path = work_path };
+    const ctx: Context = .{
+        .io = io,
+        .arena = arena,
+        .zig_exe = zig_exe,
+        .work_path = work_path,
+    };
 
     switch (mode) {
         .named => {
@@ -230,21 +246,6 @@ pub fn main(init: std.process.Init) !void {
     }
 }
 
-fn prefix(arg: []const u8, pre: []const u8) ?[]const u8 {
-    if (std.mem.startsWith(u8, arg, pre)) return arg[pre.len..];
-    return null;
-}
-
-// Shared, read-only run context threaded through the helpers.
-const Context = struct {
-    io: std.Io,
-    arena: std.mem.Allocator,
-    zig_exe: []const u8,
-    work_path: []const u8,
-};
-
-const Error = error{Failed};
-
 // Iterates exercises from `start_index` to the end, stopping at the first failure.
 // Progress is written after each passed exercise.
 fn iterateFrom(ctx: Context, start_index: usize) Error!void {