それ CLI フレームワークがなくてもできるよ / Building CLI Tools Without Frameworks

『GopherのためのCLIツール開発』最新事情 LT
https://findy.connpass.com/event/362163/

Transcript

1. ͦΕ
   $-*
   ϑϨʔϜϫʔΫ͕
   ͳͯ͘΋Ͱ͖ΔΑ 'JOEZ
   5&$)
   #"50/
   ʮ(PQIFS
   ͷͨΊͷ
   $-*
   πʔϧ։ൃʯ࠷৽ࣄ৘
   -5
   
   ,VOJXBL
2. ఻͍͑ͨ͜ͱ 2 w $-*
   πʔϧΛͭ͘Δͱ͖ϑϨʔϜϫʔΫΛ࢖Θͳ͍
   બ୒ࢶʹ΋໨Λ޲͚Α͏
   w গ͠ଥڠ͢Ε͹ɺඪ४ϥΠϒϥϦͱ୹͍ίʔυ͚ͩ
   ʢߦ͙Β͍ʣͰ͍͍ͨͯͷ͜ͱ͸࣮ݱͰ͖Δ
   w ϑϨʔϜϫʔΫΛ࢖Θͣ୹͍ίʔυͰ࣮ݱͰ͖Ε͹
   ೥୯ҐͰͷϝϯςφϯεϑϦʔʹͰ͖Δ
3. աڈ࣮੷ w ࢲͷͭ͘ΔϑϨʔϜϫʔΫΛ࢖Θͳ͍
   $-*
   πʔϧ͸ ͢΂ͯ೥୯ҐͰϝϯςφϯεϑϦʔͰಈ࡞
   
   w %FQFOEBCPU
   ͳͲ͔Β੬ऑੑ౳ͷࢦఠΛड͚Δ
   ͜ͱ͸͔ͳΓ௝͍͠ 3 
   ͨͱ͑͹
   %F/"VOJUZNFUBDIFDL
   ͸ػೳ௥ՃΛআ͚͹طଘػೳ͸೥ۙ͘ϝϯς͠ͳ͘ͱ΋
   
   
   ੬ऑੑ΋ߋ৽΋ͳ͘ϢʔεέʔεΛຬ͍ͨͤͯΔ
   
   3FOPWBUF
   ͳͲΛ࢖͑͹Ξοϓσʔτ͸͋Δఔ౓লྗԽͰ͖Δ͕ɺࢲͷ৔߹͸লྗԽͲ͜Ζ͔
   
   
   ·ͬͨ͘΍͍ͬͯͳ͍ͷͰ޻਺θϩ
4. ༻ޠͷఆٛ 4 ·ͣ͸
5. 5 ϑϨʔϜϫʔΫ
   ෦඼ͷن֨ΛܾΊΔ΋ͷɻϢʔβʔ͸ن֨ʹԊͬͨ෦඼Λ૊ΈೖΕΔ ͜ͱͰػೳΛ࣮ݱ͢Δɻͨͱ͑͹
   VSGBWFDMJ
   ΍
   TQGDPCSB
   ͳͲɻ
   ϥΠϒϥϦ
   ෦඼ͦͷ΋ͷɻϢʔβʔ͸෦඼Λ޷͖ʹ૊Έ߹ΘͤͯػೳΛ࣮ݱ͢ Δɻྫ͑͹
   KFTTFWELHP fl BHT
   ɻ಄ʹʮඪ४ʯͱͭ͘ϥΠϒϥϦ͸ ݴޠʹ૊ΈೖΕΒΕ͍ͯΔ΋ͷΛࢦ͢ɻྫ͑͹
   fl BH
   ɻ
6. 6 ϑϨʔϜϫʔΫͱϥΠϒϥϦΛݟ෼͚Δʹ͸ɺ
   ͦͷίϯϙʔωϯτͷఏڙ͢Δܕ͕ࣗ෼ͷ࣮૷͢Δ
   ίϯϙʔωϯτʹͲͷఔ౓ొ৔͢Δ͔ΛଌΔͱΑ͍ɻ
   ଟ͚Ε͹ϑϨʔϜϫʔΫతɺগͳ͚Ε͹ϥΠϒϥϦతɻ 
   ϑϨʔϜϫʔΫͱϥΠϒϥϦͷதؒతͳ΋ͷ΋͋Γ͑Δɻͨͱ͑͹
   3FBDU
   ͸υϝΠϯ૚͔Β͸
   
   
   ϥΠϒϥϦͷΑ͏ʹΈ͑ɺ7JFX
   ૚͔Β͸ϑϨʔϜϫʔΫͷΑ͏ʹΈ͑Δ
7. ϝϯςϑϦʔʹ͢Δίπ 7
8. ͳͯ͘΋͋·ΓࠔΒͳ͍ػೳΛଥڠͯ͠อकੑΛͱΔ 8 อकੑ ػೳͷଟ͞ ͭ͘Δπʔϧͷอकੑͱ
   ػೳͷଟ͞͸͓͓Αͦ
   ൓ൺྫ͢Δ
9. ͳͯ͘΋͋·ΓࠔΒͳ͍ػೳΛଥڠͯ͠อकੑΛͱΔ 9 อकੑ ػೳͷଟ͞ ໾ʹཱͨͳ͍ อक͕େม ͜͜Λ໨ࢦ͢
10. ͳͯ͘΋͋·ΓࠔΒͳ͍ػೳΛଥڠͯ͠อकੑΛͱΔ 10 อकੑ ػೳͷଟ͞ ͔͜͜Βग़ൃͯ͠ ͜͜Λ໨ࢦ͢
11. ͳͯ͘΋͋·ΓࠔΒͳ͍ػೳΛଥڠͯ͠อकੑΛͱΔ 11 อकੑ ػೳͷଟ͞ ϑϨʔϜϫʔΫΛ࢖͏ͱ͜͜ʹͳΓ͕ͪ
12. ඪ४ϥΠϒϥϦ͚ͩͷϨγϐ 12 ϝϯςϑϦʔΛ࣮ݱ͢ΔͨΊͷ
13. αϯϓϧίʔυ͸
    (JU)VC
    ʹ͋Γ·͢ 13
14. ΤϯτϦϙΠϯτͷॻ͖ํ 14 Ϩγϐ
    
15. 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਺ $-*
    ϓϩάϥϜຊମͷܕ ຊ ମ ࣮ ૷
16. 16 $-*
    ϓϩάϥϜຊମ func MainCommand(args []string, inout *cli.InOut) int { fmt.Fprintln(inout.Stdout, "Hello, World!") return 0 } ຊ ମ ࣮ ૷
17. 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
18. 18 func TestMainCommand(t *testing.T) { stdin := strings.NewReader("") stdout := &bytes.Buffer{} stderr := &bytes.Buffer{} exitStatus := MainCommand([]string{"foo", "bar"}, &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
    $-*
    ϓϩάϥϜͰ΋೉ͳ͘
    ςετΛॻ͚Δɻ
    ͜Ε͸ඪ४ೖྗʹೖྗ͞Εͨ
    ໊લʹ
    )FMMP
    Λ͚ͭͯฦ͢ྫɻ ς ε τ
19. ϑϥάͷॻ͖ํ 19 Ϩγϐ
    
20. 20 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 ࣮ ૷
21. 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
22. 22 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
23. ϑϥάͷόϦσʔγϣϯͷॻ͖ํ 23 Ϩγϐ
    
24. 24 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 ࣮ ૷
25. 25 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
26. ϔϧϓͷॻ͖ํ 26 Ϩγϐ
    
27. 27 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
28. 28 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
29. αϒίϚϯυͷॻ͖ํ 29 Ϩγϐ
    
30. 30 type SubCommand struct { Name string Description string Run Command } ຊ ମ ࣮ ૷ αϒίϚϯυͷ໊લ αϒίϚϯυߏ଄ମ αϒίϚϯυͷઆ໌ αϒίϚϯυͷॲཧ
31. 31 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 ࣮ ૷
32. 32 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
33. 33 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
34. αʔυύʔςΟ੡ϥΠϒϥϦͷϨγϐ 34 Ͳ͏ͯ͠΋ଥڠͰ͖ͳ͍ͱ͖ͷͨΊͷ ൃ ද Ͱ ͸ ׂ Ѫ
35. 35 ͜Ε͔Β঺հ͢ΔϨγϐ͸ɺඪ४ϥΠϒϥϦ͚ͩͩͱ
    ίʔυ͕௕͘ͳͬͯ͠·͏ͨΊंྠͷ࠶ൃ໌ͷײ͕
    ग़͖ͯͯ͠·͏΋ͷʹͳ͍ͬͯΔɻ ൃ ද Ͱ ͸ ׂ Ѫ
36. γΣϧิ׬ͷॻ͖ํ 36 Ϩγϐ
     ൃ ද Ͱ ͸ ׂ Ѫ
37. 37 ඪ४ϥΠϒϥϦ͚ͩͰ࣮ݱ͢Δͱߦ΄Ͳ͔͔Δɻ
    ୅ସͱͯ͠࢖͑ΔϥΠϒϥϦʢOPU
    ϑϨʔϜϫʔΫʣɿ
    w KFTTFWELHP fl BHT
    w TBHP fl BHDNQM
    w ʜ
    ࢖͍ํΛ஌Δʹ͸ͦΕͧΕͷ
    3&"%.&
    Λࢀরͯ͠΄͍͠ɻ ൃ ද Ͱ ͸ ׂ Ѫ
38. ಉ͡Φϓγϣϯͷෳ਺ճͷग़ݱ΁ͷରԠ 38 Ϩγϐ ൃ ද Ͱ ͸ ׂ Ѫ
39. 39 ࢖༻Ͱ͖ΔϥΠϒϥϦʢOPU
    ϑϨʔϜϫʔΫʣɿ
    w KFTTFWELHP fl BHT
    w BMFY fl JOUHPBSH
    w ʜ
    ࢖͍ํΛ஌Δʹ͸ͦΕͧΕͷ
    3&"%.&
    Λࢀরͯ͠΄͍͠ɻ ൃ ද Ͱ ͸ ׂ Ѫ
40. ఻͍͑ͨ͜ͱ 40 w $-*
    πʔϧΛͭ͘Δͱ͖ϑϨʔϜϫʔΫΛ࢖Θͳ͍
    બ୒ࢶʹ΋໨Λ޲͚Α͏
    w গ͠ଥڠ͢Ε͹ɺඪ४ϥΠϒϥϦͱ୹͍ίʔυ͚ͩ
    ʢߦ͙Β͍ʣͰ͍͍ͨͯͷ͜ͱ͸࣮ݱͰ͖Δ
    w ϑϨʔϜϫʔΫΛ࢖Θͣ୹͍ίʔυͰ࣮ݱͰ͖Ε͹
    ೥୯ҐͰͷϝϯςφϯεϑϦʔʹͰ͖Δ