integrate std.Io

README.md

@@ -24,7 +24,7 @@ pub fn main() !void {
         .{},
     );
 
-    try std.io.getStdOut().writer().print("Hello, {s}!\n", .{cli.username});
+    try std.debug.print("Hello, {s}!\n", .{cli.username});
 }
 
 const std = @import("std");

build.zig

@@ -45,6 +45,6 @@ pub fn build(b: *std.Build) void {
     });
     example.root_module.addImport("flags", mod);
     const run_example = b.addRunArtifact(example);
-    if (b.args) |args| run_example.addArgs(args);
+    run_example.addPassthruArgs(); // Zig 0.17+
     example_step.dependOn(&run_example.step);
 }

build.zig.zon

@@ -2,7 +2,7 @@
     .name = .flags,
     .version = "0.10.0",
     .fingerprint = 0xb0541bade61ff6b,
-    .minimum_zig_version = "0.15.1",
+    .minimum_zig_version = "0.16.0",
     // Want to limit these to only the things that really constitute "the library".
     // The hash needn't be updated by some small change to the README.
     .paths = .{

examples/colors.zig

@@ -1,14 +1,14 @@
 const std = @import("std");
 const flags = @import("flags");
 
-pub fn main() !void {
-    var gpa = std.heap.GeneralPurposeAllocator(.{}).init;
-    defer _ = gpa.deinit();
+pub fn main(init: std.process.Init) !void {
+    const io = init.io;
+    const gpa = init.gpa;
 
-    const args = try std.process.argsAlloc(gpa.allocator());
-    defer std.process.argsFree(gpa.allocator(), args);
+    const args = try init.minimal.args.toSlice(gpa);
+    defer gpa.free(args);
 
-    _ = flags.parse(args, "colors", Flags, .{
+    _ = flags.parse(io, args, "colors", Flags, .{
         // Use the `colors` option to provide a colorscheme for the error/help messages.
         // Specifying this as empty: `.colors = &.{}` will disable colors.
         // Each field is a list of type `std.io.tty.Color`.

examples/overview.zig

@@ -1,17 +1,16 @@
 const std = @import("std");
 const flags = @import("flags");
 
-pub fn main() !void {
-    var gpa = std.heap.GeneralPurposeAllocator(.{}).init;
-    defer _ = gpa.deinit();
+pub fn main(init: std.process.Init) !void {
+    const io = init.io;
+    const gpa = init.gpa;
+    const args = try init.minimal.args.toSlice(gpa);
+    defer gpa.free(args);
 
-    const args = try std.process.argsAlloc(gpa.allocator());
-    defer std.process.argsFree(gpa.allocator(), args);
-
-    const options = flags.parse(args, "overview", Flags, .{});
+    const options = flags.parse(io, args, "overview", Flags, .{});
 
     var buffer: [1024]u8 = undefined;
-    var file_writer = std.fs.File.stdout().writer(&buffer);
+    var file_writer = std.Io.File.stdout().writer(io, &buffer);
     try std.json.Stringify.value(
         options,
         .{ .whitespace = .indent_2 },

examples/trailing.zig

@@ -1,16 +1,16 @@
 const std = @import("std");
 const flags = @import("flags");
 
-pub fn main() !void {
-    var gpa = std.heap.GeneralPurposeAllocator(.{}).init;
-    defer _ = gpa.deinit();
+pub fn main(init: std.process.Init) !void {
+    const io = init.io;
+    const gpa = init.gpa;
 
-    const args = try std.process.argsAlloc(gpa.allocator());
-    defer std.process.argsFree(gpa.allocator(), args);
+    const args = try init.minimal.args.toSlice(gpa);
+    defer gpa.free(args);
 
-    const options = flags.parse(args, "trailing", Flags, .{});
+    const options = flags.parse(io, args, "trailing", Flags, .{});
 
-    var stdout_writer = std.fs.File.stdout().writer(&.{});
+    var stdout_writer = std.Io.File.stdout().writer(io, &.{});
     try std.json.Stringify.value(
         options,
         .{ .whitespace = .indent_2 },

src/ColorScheme.zig

@@ -2,7 +2,7 @@ const ColorScheme = @This();
 
 const std = @import("std");
 
-const Color = std.Io.tty.Color;
+const Color = std.Io.Terminal.Color;
 
 pub const Style = []const Color;
 

src/Help.zig

@@ -3,7 +3,7 @@ const Help = @This();
 const std = @import("std");
 const meta = @import("meta.zig");
 
-const File = std.fs.File;
+const File = std.Io.File;
 const ColorScheme = @import("ColorScheme.zig");
 const Terminal = @import("Terminal.zig");
 
@@ -17,9 +17,9 @@ pub const Usage = struct {
     command: []const u8,
     body: []const u8,
 
-    pub fn render(usage: Usage, stdout: File, colors: *const ColorScheme) void {
-        var stdout_writer = stdout.writer(&.{});
-        const term = Terminal.init(stdout, &stdout_writer.interface);
+    pub fn render(io: std.Io, usage: Usage, stdout: File, colors: *const ColorScheme) void {
+        var stdout_writer = stdout.writerStreaming(io, &.{});
+        const term = Terminal.init(io, stdout, &stdout_writer.interface) catch unreachable;
         usage.renderToTerminal(term, colors);
     }
 
@@ -75,7 +75,11 @@ pub const Usage = struct {
     fn add(usage: *Usage, item: []const u8, line_len: *usize) void {
         if (line_len.* + " ".len + item.len > max_line_len) {
             const indent_len = "Usage: ".len + usage.command.len;
-            usage.body = usage.body ++ "\n" ++ " " ** indent_len;
+            usage.body = usage.body ++ "\n" ++ comptime blk: {
+                var indent: [indent_len]u8 = undefined;
+                @memset(&indent, ' ');
+                break :blk &indent;
+            };
             line_len.* = indent_len;
         }
 
@@ -100,9 +104,9 @@ const Section = struct {
     }
 };
 
-pub fn render(help: *const Help, stdout: File, colors: *const ColorScheme) void {
-    var stdout_writer = stdout.writer(&.{});
-    const term = Terminal.init(stdout, &stdout_writer.interface);
+pub fn render(help: *const Help, io: std.Io, stdout: File, colors: *const ColorScheme) void {
+    var stdout_writer = stdout.writerStreaming(io, &.{});
+    const term = Terminal.init(io, stdout, &stdout_writer.interface) catch unreachable;
     help.usage.renderToTerminal(term, colors);
 
     if (help.description) |description| {
@@ -166,10 +170,11 @@ pub fn generate(Flags: type, info: meta.FlagsInfo, command: []const u8) Help {
         const T = meta.unwrapOptional(flag.type);
         if (@typeInfo(T) == .@"enum") {
             const variant_descriptions = meta.getDescriptions(T);
-            for (@typeInfo(T).@"enum".fields) |variant| {
+            const enum_info = @typeInfo(T).@"enum";
+            for (enum_info.field_names) |variant_name| {
                 options.add(.{
-                    .name = "  " ++ meta.toKebab(variant.name),
-                    .desc = @field(variant_descriptions, variant.name),
+                    .name = "  " ++ meta.toKebab(variant_name),
+                    .desc = @field(variant_descriptions, variant_name),
                 });
             }
         }
@@ -194,10 +199,11 @@ pub fn generate(Flags: type, info: meta.FlagsInfo, command: []const u8) Help {
             const T = meta.unwrapOptional(arg.type);
             if (@typeInfo(T) == .@"enum") {
                 const variant_descriptions = meta.getDescriptions(T);
-                for (@typeInfo(T).@"enum".fields) |variant| {
+                const enum_info = @typeInfo(T).@"enum";
+                for (enum_info.field_names) |variant_name| {
                     arguments.add(.{
-                        .name = "  " ++ meta.toKebab(variant.name),
-                        .desc = @field(variant_descriptions, variant.name),
+                        .name = "  " ++ meta.toKebab(variant_name),
+                        .desc = @field(variant_descriptions, variant_name),
                     });
                 }
             }

src/Parser.zig

@@ -14,16 +14,16 @@ args: []const [:0]const u8,
 current_arg: usize,
 colors: *const ColorScheme,
 
-fn fatal(parser: *const Parser, comptime fmt: []const u8, args: anytype) noreturn {
-    const stderr_file = std.fs.File.stderr();
-    var stderr_file_writer = stderr_file.writer(&.{});
-    const stderr = Terminal.init(stderr_file, &stderr_file_writer.interface);
+fn fatal(parser: *const Parser, io: std.Io, comptime fmt: []const u8, args: anytype) noreturn {
+    var stderr_file = std.Io.File.stderr();
+    var stderr_writer = stderr_file.writerStreaming(io, &.{});
+    const stderr = Terminal.init(io, stderr_file, &stderr_writer.interface) catch unreachable;
     stderr.print(parser.colors.error_label, "Error: ", .{});
     stderr.print(parser.colors.error_message, fmt ++ "\n", args);
     std.process.exit(1);
 }
 
-pub fn parse(parser: *Parser, Flags: type, comptime command_name: []const u8) Flags {
+pub fn parse(parser: *Parser, io: std.Io, Flags: type, comptime command_name: []const u8) Flags {
     const info = comptime meta.info(Flags);
     const help = comptime Help.generate(Flags, info, command_name);
 
@@ -39,18 +39,18 @@ pub fn parse(parser: *Parser, Flags: type, comptime command_name: []const u8) Fl
 
     next_arg: while (parser.nextArg()) |arg| {
         if (arg.len == 0) {
-            parser.fatal("empty argument", .{});
+            parser.fatal(io, "empty argument", .{});
         }
 
         if (std.mem.eql(u8, arg, "--help") or std.mem.eql(u8, arg, "-h")) {
-            help.render(std.fs.File.stdout(), parser.colors);
+            help.render(io, std.Io.File.stdout(), parser.colors);
             std.process.exit(0);
         }
 
         if (std.mem.eql(u8, arg, "--")) {
             // Blindly treat remaining arguments as positional.
             while (parser.nextArg()) |positional| {
-                if (parser.parsePositional(positional, positional_index, info.positionals, &flags) == .consumed_all) {
+                if (parser.parsePositional(io, positional, positional_index, info.positionals, &flags) == .consumed_all) {
                     break :next_arg;
                 }
                 positional_index += 1;
@@ -59,17 +59,17 @@ pub fn parse(parser: *Parser, Flags: type, comptime command_name: []const u8) Fl
 
         if (std.mem.startsWith(u8, arg, "--")) {
             inline for (info.flags) |flag| if (std.mem.eql(u8, arg, flag.flag_name)) {
-                @field(flags, flag.field_name) = parser.parseOption(flag.type, flag.flag_name);
+                @field(flags, flag.field_name) = parser.parseOption(io, flag.type, flag.flag_name);
                 @field(passed, flag.field_name) = true;
                 continue :next_arg;
             };
 
-            parser.fatal("unrecognized flag: {s}", .{arg});
+            parser.fatal(io, "unrecognized flag: {s}", .{arg});
         }
 
         if (std.mem.startsWith(u8, arg, "-")) {
             if (arg.len == 1) {
-                parser.fatal("unrecognized argument: '-'", .{});
+                parser.fatal(io, "unrecognized argument: '-'", .{});
             }
 
             const switch_set = arg[1..];
@@ -79,31 +79,32 @@ pub fn parse(parser: *Parser, Flags: type, comptime command_name: []const u8) Fl
                         // Removing this check would allow formats like:
                         // `$ <cmd> -abc value-for-a value-for-b value-for-c`
                         if (flag.type != bool and i < switch_set.len - 1) {
-                            parser.fatal("missing value after switch: {c}", .{switch_char});
+                            parser.fatal(io, "missing value after switch: {c}", .{switch_char});
                         }
                         @field(flags, flag.field_name) = parser.parseOption(
+                            io,
                             flag.type,
                             &.{ '-', switch_char },
                         );
                         @field(passed, flag.field_name) = true;
                         continue :next_switch;
                     }
                 };
-                parser.fatal("unrecognized switch: {c}", .{ch});
+                parser.fatal(io, "unrecognized switch: {c}", .{ch});
             }
             continue :next_arg;
         }
 
         inline for (info.subcommands) |cmd| {
             if (std.mem.eql(u8, arg, cmd.command_name)) {
-                const cmd_flags = parser.parse(cmd.type, command_name ++ " " ++ cmd.command_name);
+                const cmd_flags = parser.parse(io, cmd.type, command_name ++ " " ++ cmd.command_name);
                 flags.command = @unionInit(@TypeOf(flags.command), cmd.field_name, cmd_flags);
                 passed.command = true;
                 continue :next_arg;
             }
         }
 
-        if (parser.parsePositional(arg, positional_index, info.positionals, &flags) == .consumed_all) {
+        if (parser.parsePositional(io, arg, positional_index, info.positionals, &flags) == .consumed_all) {
             break :next_arg;
         }
         positional_index += 1;
@@ -115,7 +116,7 @@ pub fn parse(parser: *Parser, Flags: type, comptime command_name: []const u8) Fl
                 .bool => false,
                 .optional => null,
                 else => {
-                    parser.fatal("missing required flag: {s}", .{flag.flag_name});
+                    parser.fatal(io, "missing required flag: {s}", .{flag.flag_name});
                 },
             };
     };
@@ -126,21 +127,22 @@ pub fn parse(parser: *Parser, Flags: type, comptime command_name: []const u8) Fl
                 switch (@typeInfo(pos.type)) {
                     .optional => null,
                     else => {
-                        parser.fatal("missing required argument: {s}", .{pos.arg_name});
+                        parser.fatal(io, "missing required argument: {s}", .{pos.arg_name});
                     },
                 };
         }
     }
 
     if (info.subcommands.len > 0 and !passed.command) {
-        parser.fatal("missing subcommand", .{});
+        parser.fatal(io, "missing subcommand", .{});
     }
 
     return flags;
 }
 
 fn parsePositional(
     parser: *Parser,
+    io: std.Io,
     arg: [:0]const u8,
     index: usize,
     comptime positionals: []const meta.Positional,
@@ -152,42 +154,44 @@ fn parsePositional(
             parser.current_arg = parser.args.len;
             return .consumed_all;
         }
-        parser.fatal("unexpected argument: {s}", .{arg});
+        parser.fatal(io, "unexpected argument: {s}", .{arg});
     }
 
     switch (index) {
         inline 0...positionals.len - 1 => |i| {
             const positional = positionals[i];
             const T = meta.unwrapOptional(positional.type);
-            @field(flags.positional, positional.field_name) = parser.parseValue(T, arg);
+            @field(flags.positional, positional.field_name) = parser.parseValue(io, T, arg);
             return .consumed_one;
         },
 
         else => unreachable,
     }
 }
 
-fn parseOption(parser: *Parser, T: type, option_name: []const u8) T {
+fn parseOption(parser: *Parser, io: std.Io, T: type, option_name: []const u8) T {
     if (T == bool) return true;
 
     const value = parser.nextArg() orelse {
-        parser.fatal("missing value for '{s}'", .{option_name});
+        parser.fatal(io, "missing value for '{s}'", .{option_name});
     };
 
-    return parser.parseValue(meta.unwrapOptional(T), value);
+    return parser.parseValue(io, meta.unwrapOptional(T), value);
 }
 
-fn parseValue(parser: *const Parser, T: type, arg: [:0]const u8) T {
+fn parseValue(parser: *const Parser, io: std.Io, T: type, arg: [:0]const u8) T {
     if (T == []const u8 or T == [:0]const u8) return arg;
 
     switch (@typeInfo(T)) {
         .int => |info| return std.fmt.parseInt(T, arg, 10) catch |err| {
             switch (err) {
                 error.Overflow => parser.fatal(
+                    io,
                     "value out of bounds for {d}-bit {s} integer: {s}",
                     .{ info.bits, @tagName(info.signedness), arg },
                 ),
                 error.InvalidCharacter => parser.fatal(
+                    io,
                     "expected integer number, found '{s}'",
                     .{arg},
                 ),
@@ -196,18 +200,18 @@ fn parseValue(parser: *const Parser, T: type, arg: [:0]const u8) T {
 
         .float => return std.fmt.parseFloat(T, arg) catch |err| switch (err) {
             error.InvalidCharacter => {
-                parser.fatal("expected numerical value, found '{s}'", .{arg});
+                parser.fatal(io, "expected numerical value, found '{s}'", .{arg});
             },
         },
 
         .@"enum" => |info| {
-            inline for (info.fields) |field| {
-                if (std.mem.eql(u8, arg, meta.toKebab(field.name))) {
-                    return @enumFromInt(field.value);
+            inline for (info.field_names, info.field_values) |field_name, field_value| {
+                if (std.mem.eql(u8, arg, meta.toKebab(field_name))) {
+                    return @fromBackingInt(@intCast(field_value));
                 }
             }
 
-            parser.fatal("unrecognized option: '{s}'", .{arg});
+            parser.fatal(io, "unrecognized option: '{s}'", .{arg});
         },
 
         else => comptime meta.compileError("invalid flag type: {s}", .{@typeName(T)}),