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,VOJXBL 

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બ୒ࢶʹ΋໨Λ޲͚Α͏
w গ͠ଥڠ͢Ε͹ɺඪ४ϥΠϒϥϦͱ୹͍ίʔυ͚ͩ
ʢߦ͙Β͍ʣͰ͍͍ͨͯͷ͜ͱ͸࣮ݱͰ͖Δ
w ϑϨʔϜϫʔΫΛ࢖Θͣ୹͍ίʔυͰ࣮ݱͰ͖Ε͹
೥୯ҐͰͷϝϯςφϯεϑϦʔʹͰ͖Δ 

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w %FQFOEBCPU
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͜ͱ͸͔ͳΓ௝͍͠ 3 
ͨͱ͑͹
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͸ػೳ௥ՃΛআ͚͹طଘػೳ͸೥ۙ͘ϝϯς͠ͳ͘ͱ΋


੬ऑੑ΋ߋ৽΋ͳ͘ϢʔεέʔεΛຬ͍ͨͤͯΔ

3FOPWBUF
ͳͲΛ࢖͑͹Ξοϓσʔτ͸͋Δఔ౓লྗԽͰ͖Δ͕ɺࢲͷ৔߹͸লྗԽͲ͜Ζ͔


·ͬͨ͘΍͍ͬͯͳ͍ͷͰ޻਺θϩ 

༻ޠͷఆٛ 4 ·ͣ͸ 

5 ϑϨʔϜϫʔΫ
෦඼ͷن֨ΛܾΊΔ΋ͷɻϢʔβʔ͸ن֨ʹԊͬͨ෦඼Λ૊ΈೖΕΔ
͜ͱͰػೳΛ࣮ݱ͢Δɻͨͱ͑͹
VSGBWFDMJ
΍
TQGDPCSB
ͳͲɻ
ϥΠϒϥϦ
෦඼ͦͷ΋ͷɻϢʔβʔ͸෦඼Λ޷͖ʹ૊Έ߹ΘͤͯػೳΛ࣮ݱ͢Δɻ
ྫ͑͹
KFTTFWELHP fl BHT
ɻಛʹϥΠϒϥϦͷ͏ͪඪ४ϥΠϒϥϦͱ͸
ݴޠʹ૊ΈೖΕΒΕ͍ͯΔ΋ͷΛࢦ͢ɻྫ͑͹
fl BH
ɻ 

6 ϑϨʔϜϫʔΫͱϥΠϒϥϦΛݟ෼͚Δʹ͸ɺ
ͦͷίϯϙʔωϯτͷఏڙ͢Δܕ͕ࣗ෼ͷ࣮૷͢Δ
ίϯϙʔωϯτʹͲͷఔ౓୅ସෆՄೳͳ΋ͷͱͯ͠
ొ৔͢Δ͔ΛଌΔͱΑ͍ɻ
ଟ͚Ε͹ϑϨʔϜϫʔΫతɺগͳ͚Ε͹ϥΠϒϥϦతɻ 
ϑϨʔϜϫʔΫͱϥΠϒϥϦͷதؒతͳ΋ͷ΋͋Γ͑Δɻͨͱ͑͹
3FBDU
͸υϝΠϯ૚͔Β͸


ϥΠϒϥϦͷΑ͏ʹΈ͑ɺ7JFX
૚͔Β͸ϑϨʔϜϫʔΫͷΑ͏ʹΈ͑Δ 

ϝϯςϑϦʔʹ͢Δίπ 7 ͕͜͜ࠓճͷϙΠϯτ 

ͳͯ͘΋͋·ΓࠔΒͳ͍ػೳΛଥڠͯ͠อकੑΛͱΔ 8 อकੑ ػೳͷଟ͞ ͭ͘Δπʔϧͷอकੑͱ
ػೳͷଟ͞͸͓͓Αͦ
൓ൺྫ͢Δ 

ͳͯ͘΋͋·ΓࠔΒͳ͍ػೳΛଥڠͯ͠อकੑΛͱΔ 9 อकੑ ػೳͷଟ͞ ໾ʹཱͨͳ͍ อक͕େม ͜͜Λ໨ࢦ͢ 

ͳͯ͘΋͋·ΓࠔΒͳ͍ػೳΛଥڠͯ͠อकੑΛͱΔ 10 อकੑ ػೳͷଟ͞ ͔͜͜Βग़ൃͯ͠ ͜͜Λ໨ࢦ͢ 

ͳͯ͘΋͋·ΓࠔΒͳ͍ػೳΛଥڠͯ͠อकੑΛͱΔ 11 อकੑ ػೳͷଟ͞ ϑϨʔϜϫʔΫΛ࢖͏ͱ͜͜ʹͳΓ͕ͪ 

ඪ४ϥΠϒϥϦ͚ͩͷϨγϐ 12 ϝϯςϑϦʔΛ࣮ݱ͢ΔͨΊͷ 

αϯϓϧίʔυ͸
(JU)VC
ʹ͋Γ·͢ 13 

ΤϯτϦϙΠϯτͷॻ͖ํ 14 Ϩγϐ
 

15 type InOut struct { Stdin io.Reader Stdout io.Writer Stderr io.Writer } func NewInOut() *InOut { return &InOut{ Stdin: os.Stdin, Stdout: os.Stdout, Stderr: os.Stderr, } } type Command func(args []string, inout *InOut) int func Run(c Command) { args := os.Args[1:] exitStatus := c(args, NewInOut()) os.Exit(exitStatus) } ඪ४ೖग़ྗΛ·ͱΊͨߏ଄ମɻ
JP3FBE$MPTFS
΍
JP8SJUF$MPTFS
Ͱ΋Α͍ɻ
ςετ࣌ʹ͸ద౰ͳِ෺ͱࠩ͠ସ͑Δ ຊ෺ͷඪ४ೖग़ྗΛ࡞Δؔ਺ $PNNBOE
ͷ࣮ߦؔ਺ $-*
ϓϩάϥϜຊମͷܕɻςετΛ
͠΍͘͢͢ΔͨΊʹ࢖͏ ຊ ମ ࣮ ૷ 

16 $-*
ϓϩάϥϜຊମ func MainCommand(args []string, inout *cli.InOut) int { fmt.Fprintln(inout.Stdout, "Hello, World!") return 0 } ຊ ମ ࣮ ૷ 

17 NBJO
ؔ਺͸͜Ε͚ͩ func main() { cli.Run(MainCommand) } ຊ ମ ࣮ ૷ 

func TestMainCommand(t *testing.T) { stdin := strings.NewReader("") stdout := &bytes.Buffer{} stderr := &bytes.Buffer{} exitStatus := MainCommand([]string{}, &cli.InOut{ Stdin: stdin, Stdout: stdout, Stderr: stderr, }) if exitStatus != 0 { t.Errorf("unexpected exit status: %d", exitStatus) } expected := "Hello, World!" if stdout.String() != expected { t.Errorf("want %q, got %q", expected, stdout.String()) } } $-*
ϓϩάϥϜͷςετɻ
͔ͳΓ͋ͬ͞Γॻ͚Δ ς ε τ 

19 func TestMainCommand(t *testing.T) { stdin := strings.NewReader("foo\nbar\n") stdout := &bytes.Buffer{} stderr := &bytes.Buffer{} exitStatus := MainCommand([]string{}, &cli.InOut{ Stdin: stdin, Stdout: stdout, Stderr: stderr, }) if exitStatus != 0 { t.Errorf("unexpected exit status: %d", exitStatus) } expected := "Hello, foo!\nHello, bar!\n" if stdout.String() != expected { t.Errorf("want %q, got %q", expected, stdout.String()) } } .$1
αʔόʔͳͲର࿩తͳ
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ϓϩάϥϜͰ΋೉ͳ͘
ςετΛॻ͚Δɻ
͜Ε͸ඪ४ೖྗʹೖྗ͞Εͨ
໊લʹ
)FMMP
Λ͚ͭͯฦ͢ྫɻ ς ε τ 

ϑϥάͷॻ͖ํ 20 Ϩγϐ
 

21 type Options struct { Foo string Bar string Help bool } func ParseOptions(args []string, inout *cli.InOut) (*Options, error) { flags := flag.NewFlagSet("recipe2", flag.ContinueOnError) flags.SetOutput(inout.Stderr) options := &Options{} flags.StringVar(&options.Foo, "foo", "", "Foo") flags.StringVar(&options.Bar, "bar", "", "Bar") if err := flags.Parse(args); err != nil { if errors.Is(err, flag.ErrHelp) { options.Help = true return options, nil } return nil, err } return options, nil } $-*
ϓϩάϥϜͷΦϓγϣϯߏ଄ମ Φϓγϣϯղੳؔ਺ ຊ ମ ࣮ ૷ 

func TestParseOptions(t *testing.T) { testCases := []struct { Input []string Expected *Options }{ { Input: []string{"-foo", "foo", "-bar", "bar"}, Expected: &Options{ Foo: "foo", Bar: "bar", }, }, { Input: []string{"-h"}, Expected: &Options{ Help: true, }, }, } Φϓγϣϯղੳؔ਺ͷςετ ೖྗͱͳΔҾ਺Λఆٛͯ͠ ظ଴͢ΔΦϓγϣϯߏ଄ମΛॻ͘ ς ε τ 

23 for _, testCase := range testCases { stdout := &bytes.Buffer{} stderr := &bytes.Buffer{} opts, err := ParseOptions(testCase.Input, &cli.InOut{ Stdin: strings.NewReader(""), Stdout: stdout, Stderr: stderr, }) if err != nil { t.Fatalf("failed to parse options: %v", err) } if !reflect.DeepEqual(opts, testCase.Expected) { t.Error(cmp.Diff(opts, testCase.Expected)) } } } ςʔϒϧۦಈͰςετ͢Δ ς ε τ 

ϑϥάͷόϦσʔγϣϯͷॻ͖ํ 24 Ϩγϐ
 

25 type Options struct { SomethingRequired string Help bool } func ParseOptions(args []string, inout *cli.InOut) (*Options, error) { flags := flag.NewFlagSet("recipe3", flag.ContinueOnError) flags.SetOutput(inout.Stderr) options := &Options{} flags.StringVar(&options.SomethingRequired, "something-required", "", "Something required") if err := flags.Parse(args); err != nil { if errors.Is(err, flag.ErrHelp) { options.Help = true return options, nil } return nil, err } if options.SomethingRequired == "" { return nil, errors.New("something-required is required") } return options, nil } $-*
ϓϩάϥϜͷΦϓγϣϯߏ଄ମ Φϓγϣϯղੳؔ਺Λ࣮૷͢Δ όϦσʔγϣϯ͢Δ ຊ ମ ࣮ ૷ 

26 func TestParseOptions_Error(t *testing.T) { testCases := []struct { Input []string }{ { Input: []string{}, }, } for _, testCase := range testCases { stdout := &bytes.Buffer{} stderr := &bytes.Buffer{} _, err := ParseOptions(testCase.Input, &cli.InOut{ Stdin: strings.NewReader(""), Stdout: stdout, Stderr: stderr, }) if err == nil { t.Fatalf("expected error, got nil") } } } ςʔϒϧۦಈͰςετ͢Δ ඞਢͷҾ਺͕ͳ͚Ε͹ ΤϥʔʹͳΔ͜ͱΛظ଴͢Δ ς ε τ 

ϔϧϓͷॻ͖ํ 27 Ϩγϐ
 

28 func ParseOptions(args []string, inout *cli.InOut) (*Options, error) { flags := flag.NewFlagSet("recipe4", flag.ContinueOnError) flags.SetOutput(inout.Stderr) options := &Options{} flags.StringVar(&options.Foo, "foo", "", "foo") flags.StringVar(&options.Bar, "bar", "", "bar") flags.Usage = func() { inout.Stderr.Write([]byte("Usage: recipe4 [options]\n")) inout.Stderr.Write([]byte("OPTIONS\n")) flags.PrintDefaults() } if err := flags.Parse(args); err != nil { if errors.Is(err, flag.ErrHelp) { options.Help = true return options, nil } return nil, err } return options, nil } ຊ ମ ࣮ ૷ Φϓγϣϯղੳؔ਺ ϔϧϓͷදࣔॲཧ 

29 func TestFlagUsage(t *testing.T) { stdin := strings.NewReader("") stdout := &bytes.Buffer{} stderr := &bytes.Buffer{} _, err := ParseOptions([]string{"-h"}, &cli.InOut{ Stdin: stdin, Stdout: stdout, Stderr: stderr, }) if err != nil { t.Fatalf("failed to parse options: %v", err) } expected := `Usage: recipe4 [options] OPTIONS -bar string bar -foo string foo ` if stderr.String() != expected { t.Errorf("want %q, got %q", expected, stderr.String()) } } ς ε τ ϔϧϓΛදࣔͤ͞Δ ظ଴ͱͷҰகΛ֬ೝ 

αϒίϚϯυͷॻ͖ํ 30 Ϩγϐ
 

31 type SubCommand struct { Name string Description string Run Command } ຊ ମ ࣮ ૷ αϒίϚϯυͷ໊લ αϒίϚϯυߏ଄ମ αϒίϚϯυͷઆ໌ αϒίϚϯυͷॲཧ 

32 Φϓγϣϯͷղੳ αϒίϚϯυͷ͋ΔίϚϯυΛએݴ αϒίϚϯυͷىಈ ϔϧϓͷ४උ func NewCommand(name string, cmds []SubCommand) Command { return func(args []string, inout *InOut) int { flags := flag.NewFlagSet(name, flag.ContinueOnError) flags.SetOutput(inout.Stderr) flags.Usage = func() { fmt.Fprintf(inout.Stderr, "Usage: %s [command]\n\n", name) fmt.Fprintf(inout.Stderr, "COMMANDS\n") for _, cmd := range cmds { fmt.Fprintf(inout.Stderr, " %s\n \t%s\n", cmd.Name, cmd.Description) } } if err := flags.Parse(args); err != nil { if err == flag.ErrHelp { return 0 } return 1 } if flags.NArg() == 0 { fmt.Fprintf(inout.Stderr, "error: no command provided\n") flags.Usage() return 1 } for _, cmd := range cmds { if cmd.Name == flags.Arg(0) { return cmd.Run(flags.Args()[1:], inout) } } fmt.Fprintf(inout.Stderr, "error: unknown command: %s\n", flags.Arg(0)) flags.Usage() return 1 } } ຊ ମ ࣮ ૷ 

33 func TestNewCommand(t *testing.T) { s1 := SubCommand{ Name: "one", Description: "1st subcommand", Run: func(args []string, inout *ProcInout) int { fmt.Fprintln(inout.Stdout, "1") return 0 }, } s2 := SubCommand{ Name: "two", Description: "2nd subcommand", Run: func(args []string, inout *ProcInout) int { fmt.Fprintln(inout.Stdout, "2") return 0 }, } ς ε τ ِͷαϒίϚϯυΛ༻ҙ ِͷαϒίϚϯυΛ༻ҙ 

34 stdin := strings.NewReader("") stdout := &bytes.Buffer{} stderr := &bytes.Buffer{} cmd := NewCommand("test", []SubCommand{s1, s2}) exitStatus := cmd([]string{"two"}, &ProcInout{ Stdin: stdin, Stdout: stdout, Stderr: stderr, }) if exitStatus != 0 { t.Errorf("expected exit status 0, got %d", exitStatus) } if stdout.String() != "2\n" { t.Errorf("expected output '2', got %q", stdout.String()) } } ς ε τ ͋ͱ͸͍ͭ΋௨Γςετ 

఻͍͑ͨ͜ͱ 35 w $-*
πʔϧΛͭ͘Δͱ͖ϑϨʔϜϫʔΫΛ࢖Θͳ͍
બ୒ࢶʹ΋໨Λ޲͚Α͏
w গ͠ଥڠ͢Ε͹ɺඪ४ϥΠϒϥϦͱ୹͍ίʔυ͚ͩ
ʢߦ͙Β͍ʣͰ͍͍ͨͯͷ͜ͱ͸࣮ݱͰ͖Δ
w ϑϨʔϜϫʔΫΛ࢖Θͣ୹͍ίʔυͰ࣮ݱͰ͖Ε͹
೥୯ҐͰͷϝϯςφϯεϑϦʔʹͰ͖Δ 

αʔυύʔςΟ੡ϥΠϒϥϦͷϨγϐ 36 Ͳ͏ͯ͠΋ଥڠͰ͖ͳ͍ͱ͖ͷͨΊͷ ൃ ද Ͱ ͸ ׂ Ѫ 

37 ͜Ε͔Β঺հ͢ΔϨγϐ͸ɺඪ४ϥΠϒϥϦ͚ͩͩͱ
ίʔυ͕௕͘ͳͬͯ͠·͏ͨΊंྠͷ࠶ൃ໌ͷײ͕
ग़͖ͯͯ͠·͏΋ͷʹͳ͍ͬͯΔɻ ൃ ද Ͱ ͸ ׂ Ѫ 

γΣϧิ׬ͷॻ͖ํ 38 Ϩγϐ
 ൃ ද Ͱ ͸ ׂ Ѫ 

39 ඪ४ϥΠϒϥϦ͚ͩͰ࣮ݱ͢Δͱߦ΄Ͳ͔͔Δ
ʢαϯϓϧίʔυͷ
SFDJQF
Λࢀরʣɻ
୅ସͱͯ͠࢖͑ΔϥΠϒϥϦʢOPU
ϑϨʔϜϫʔΫʣɿ
w KFTTFWELHP fl BHT
w TBHP fl BHDNQM
w ʜ
࢖͍ํΛ஌Δʹ͸ͦΕͧΕͷ
3&"%.&
Λࢀরͯ͠΄͍͠ɻ ൃ ද Ͱ ͸ ׂ Ѫ 

ಉ͡Φϓγϣϯͷෳ਺ճͷग़ݱ΁ͷରԠ 40 Ϩγϐ ൃ ද Ͱ ͸ ׂ Ѫ 

41 ࢖༻Ͱ͖ΔϥΠϒϥϦʢOPU
ϑϨʔϜϫʔΫʣɿ
w KFTTFWELHP fl BHT
w BMFY fl JOUHPBSH
w ʜ
࢖͍ํΛ஌Δʹ͸ͦΕͧΕͷ
3&"%.&
Λࢀরͯ͠΄͍͠ɻ ൃ ද Ͱ ͸ ׂ Ѫ