CLI ツール開発を支える技術 2019春 / Techniques that support building CLI tools, 2019 Spring

talked on https://golangtokyo.connpass.com/event/129067/

Transcript

1. ©2019 Wantedly, Inc.
   $-*πʔϧ։ൃΛࢧ͑Δٕज़य़
   Techniques that support building CLI tools, 2019 Spring
   golang.tokyo #24
   May 20, 2019 - Masayuki izumi
   

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2. ϖʔδλΠτϧ ϖʔδαϒλΠτϧ
   ©2019 Wantedly, Inc.
   (P$PO4QSJOH͓͔ͭΕ͞·Ͱͨ͠
   ӡӦͷΈͳ͞ΜɺొஃऀͷΈͳ͞ΜɺࢀՃ͞ΕͨΈͳ͞Μ#
   

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3. ©2019 Wantedly, Inc.
   

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4. ©2019 Wantedly, Inc.
   

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5. ϖʔδλΠτϧ ϖʔδαϒλΠτϧ
   ©2019 Wantedly, Inc.
   ͓Θ͔Γ͍͚ͨͩͨͩΖ͏͔
   

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6. ©2019 Wantedly, Inc.
   

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7. ϖʔδλΠτϧ ϖʔδαϒλΠτϧ
   ©2019 Wantedly, Inc.
   
   ͔ͿΒͳ͍Α͏ͳ࿩Λ͠·͢
   
   
   

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8. ©2019 Wantedly, Inc.
   $-*πʔϧ։ൃΛࢧ͑Δٕज़य़
   Techniques that support building CLI tools, 2019 Spring
   golang.tokyo #24
   May 20, 2019 - Masayuki izumi
   

   View Slide

9. ©2019 Wantedly, Inc.
   $ whoami
   @izumin5210
   Wantedly, Inc.
   ‣ Wantedly People
   - Application Engineer (Go, Ruby, Web
   Frontend)
   ‣ Interested in…
   - Microservices
   - Developer Productivity
   - Developer Experience
   

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10. ©2019 Wantedly, Inc.
    Talk abst and desc
    

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11. ©2019 Wantedly, Inc.
    Building CLI tools 101
    Section subhead
    

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12. ©2019 Wantedly, Inc.
    (PͰ$-*ͱ͍͑͹ʜ
    Α͘ฉ͘ศརύοέʔδ܈
    ‣ ͪΐͬͱศརͳϑϥάύʔα
    AqBHA TUBOEBSEMJC JNQPSUFECZQLHT
    
    ATQGQqBHA TUBST JNQPSUFECZQLHT
    
    AKFTTFWELHPqBHTA TUBST JNQPSUFECZQLHT
    
    ABMFDUIPNBTLJOHQJOA TUBST JNQPSUFECZQLHT
    
    #VJMEJOH$-*UPPMT
    ਺ࣈ͸͢΂ͯ࣌఺ͷ΋ͷ
    TUBS਺͸HJUIVCDPNɺඃJNQPSU਺͸HPEPDPSHΛࢀর
    

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13. ©2019 Wantedly, Inc.
    (PͰ$-*ͱ͍͑͹ʜ
    Α͘ฉ͘ศརύοέʔδ܈
    ‣ ͪΐͬͱศརͳϑϥάύʔα
    AqBHA TUBOEBSEMJC JNQPSUFECZQLHT
    
    ATQGQqBHA TUBST JNQPSUFECZQLHT
    
    AKFTTFWELHPqBHTA TUBST JNQPSUFECZQLHT
    
    ABMFDUIPNBTLJOHQJOA TUBST JNQPSUFECZQLHT
    
    #VJMEJOH$-*UPPMT
    ਺ࣈ͸͢΂ͯ࣌఺ͷ΋ͷ
    TUBS਺͸HJUIVCDPNɺඃJNQPSU਺͸HPEPDPSHΛࢀর
    AqBHA͕-POHPQUJPOະରԠͳͷ͕ಋೖͷେ͖ͳϞνϕʔγϣϯ
    AQqBHAAqBHAͷ*'Λ౿ऻͭͭ͠104*9(/6TUZMFରԠ
    AHPqBHTATUSVDUUBHΛΈͯ͏·͘΍Δ
    ALJOHQJOAqVFOUTUZMFͳ"1*Ͱ͔͍͍ͬ͜
    

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14. ©2019 Wantedly, Inc.
    (PͰ$-*ͱ͍͑͹ʜ
    Α͘ฉ͘ศརύοέʔδ܈
    ‣ ͪΐͬͱศརͳϑϥάύʔα
    AqBHA TUBOEBSEMJC JNQPSUFECZQLHT
    
    ATQGQqBHA TUBST JNQPSUFECZQLHT
    
    AKFTTFWELHPqBHTA TUBST JNQPSUFECZQLHT
    
    ABMFDUIPNBTLJOHQJOA TUBST JNQPSUFECZQLHT
    
    #VJMEJOH$-*UPPMT
    ਺ࣈ͸͢΂ͯ࣌఺ͷ΋ͷ
    TUBS਺͸HJUIVCDPNɺඃJNQPSU਺͸HPEPDPSHΛࢀর
    

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15. ©2019 Wantedly, Inc.
    (PͰ$-*ͱ͍͑͹ʜ
    Α͘ฉ͘ศརύοέʔδ܈
    ‣ ͪΐͬͱศརͳϑϥάύʔα
    AqBHA TUBOEBSEMJC JNQPSUFECZQLHT
    
    ATQGQqBHA TUBST JNQPSUFECZQLHT
    
    AKFTTFWELHPqBHTA TUBST JNQPSUFECZQLHT
    
    ABMFDUIPNBTLJOHQJOA TUBST JNQPSUFECZQLHT
    
    ‣ αϒίϚϯυ ϔϧϓੜ੒ ίϚϯυ࣮ߦલޙͷϑοΫͳͲͷػೳΛ࣋ͭଟػೳϑϨʔϜϫʔΫ
    ATQGDPCSBA TUBST JNQPSUFECZQLHT
    
    AVSGBWFDMJA TUBST JNQPSUFECZQLHT
    
    ANJUDIFMMIDMJA TUBST JNQPSUFECZQLHT
    
    #VJMEJOH$-*UPPMT
    ਺ࣈ͸͢΂ͯ࣌఺ͷ΋ͷ
    TUBS਺͸HJUIVCDPNɺඃJNQPSU਺͸HPEPDPSHΛࢀর
    

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16. ©2019 Wantedly, Inc.
    ࠷ॳͷٕज़બఆ
    ن໛ײɾػೳཁ͔݅ΒΞϓϩʔνΛܾΊΔ
    ‣ ͭ͘Γ͍ͨπʔϧ͸ͲΕ͘Β͍ͷن໛ʹͳΔ͔
    ௒୯ػೳɾ͍͔ͭ͘ͷϑϥάͱҾ਺͕͋Δ͚ͩ
    FHADEA AMTA AJ[VNJOHFYA
    ͍͔ͭ͘αϒίϚϯυʢαϒαϒίϚϯυ ʜʣΛ΋ͭ
    FHAEPDLFSA ALVCFDUMA AJ[VNJOHSBQJA AJ[VNJOTVCFFA
    #VJMEJOH$-*UPPMT
    

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17. ©2019 Wantedly, Inc.
    ࠷ॳͷٕज़બఆ
    ن໛ײɾػೳཁ͔݅ΒΞϓϩʔνΛܾΊΔ
    ‣ ͭ͘Γ͍ͨπʔϧ͸ͲΕ͘Β͍ͷن໛ʹͳΔ͔
    ௒୯ػೳɾ͍͔ͭ͘ͷϑϥάͱҾ਺͕͋Δ͚ͩ
    FHADEA AMTA AJ[VNJOHFYA
    ͍͔ͭ͘αϒίϚϯυʢαϒαϒίϚϯυ ʜʣΛ΋ͭ
    FHAEPDLFSA ALVCFDUMA AJ[VNJOHSBQJA AJ[VNJOTVCFFA
    ‣ ͲΕ͘Β͍ͷػೳੑ͕ඞཁ͔
    ϑϥά
    ɾ؀ڥม਺ɾઃఆϑΝΠϧʜͲ͜·Ͱඞཁʁ
    #VJMEJOH$-*UPPMT
    

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18. ©2019 Wantedly, Inc.
    switch res := flag.Arg(0); res {
    case "topic":
    if flag.NArg() < 2 {
    return errors.New("must specify subcommand: [create]")
    }
    switch cmd := flag.Arg(1); cmd {
    case "create":
    name := flag.Arg(2)
    if name == "" {
    return errors.New("must specify a topic name")
    }
    _, err := client.CreateTopic(ctx, name)
    if err != nil {
    return err
    }
    case "publish":
    body := flag.Arg(2)
    if body == "" {
    return errors.New("must specify a message body")
    }
    if err := requireString("topic", topicID); err != nil {
    return err
    }
    topic, err := getTopic(ctx, *topicID, client)
    if err != nil {
    return err
    }
    _ = topic.Publish(ctx, &pubsub.Message{Data: []byte(body)})
    topic.Stop()
    default:
    return fmt.Errorf("unknown subcommand: %q for %s", cmd, res)
    }
    case "subscription":
    if flag.NArg() < 2 {
    ӈͷίʔυʢJ[VNJOQVCTVCDMJʣ͸ѹ౗తʹࠔͬͯ
    ͍Δ͜ͱ͕͋ΓɺͦΕΛര଎Ͱղܾͨͯ͘͠ॻ͍ͨͱ͖
    ͷ΋ͷ
    ن໛ײɾεϐʔυײʹΑͬͯ͸
    ͜͏͍͏ίʔυ͔Β͸͡ΊΔͷ΋ѱ͘ͳ͍ͷ͔΋ʜʁ
    

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19. ©2019 Wantedly, Inc.
    ࠷ॳͷٕज़બఆ
    ·Α͍ͬͯΔͱ͖ͷબఆϑϩʔ
    ‣ ͸΍͘ղܾ͍ͨ͠໰୊͕͋ΔʂͳΜͰ΋͍͍͔Βૣ͘࡞Γ͍ͨʂ
    Ұ୴AqBHA͔AQqBHAͰ͓஡Λ୙ͭͭ͠ര଎Ͱͭͬͯ͘ɺ͋ͱ͔Βߟ͑·͠ΐ͏
    αϒίϚϯυ͕ඞཁͳ৔߹͸ADPCSBAΛ࢖͍·͠ΐ͏
    #VJMEJOH$-*UPPMT
    

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20. ©2019 Wantedly, Inc.
    ࠷ॳͷٕज़બఆ
    ·Α͍ͬͯΔͱ͖ͷબఆϑϩʔ
    ‣ ͸΍͘ղܾ͍ͨ͠໰୊͕͋ΔʂͳΜͰ΋͍͍͔Βૣ͘࡞Γ͍ͨʂ
    Ұ୴AqBHA͔AQqBHAͰ͓஡Λ୙ͭͭ͠ര଎Ͱͭͬͯ͘ɺ͋ͱ͔Βߟ͑·͠ΐ͏
    αϒίϚϯυ͕ඞཁͳ৔߹͸ADPCSBAΛ࢖͍·͠ΐ͏
    ‣ αϒίϚϯυ͸͍·ͷͱ͜Ζ࢖͏༧ఆ͸ͳ͍
    AQqBHA͕͓͢͢ΊͰ͢
    #VJMEJOH$-*UPPMT
    

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21. ©2019 Wantedly, Inc.
    ࠷ॳͷٕज़બఆ
    ·Α͍ͬͯΔͱ͖ͷબఆϑϩʔ
    ‣ ͸΍͘ղܾ͍ͨ͠໰୊͕͋ΔʂͳΜͰ΋͍͍͔Βૣ͘࡞Γ͍ͨʂ
    Ұ୴AqBHA͔AQqBHAͰ͓஡Λ୙ͭͭ͠ര଎Ͱͭͬͯ͘ɺ͋ͱ͔Βߟ͑·͠ΐ͏
    αϒίϚϯυ͕ඞཁͳ৔߹͸ADPCSBAΛ࢖͍·͠ΐ͏
    ‣ αϒίϚϯυ͸͍·ͷͱ͜Ζ࢖͏༧ఆ͸ͳ͍
    AQqBHA͕͓͢͢ΊͰ͢
    ‣ ؀ڥม਺ɾઃఆϑΝΠϧΛ࢖͏༧ఆ͕͋Δ
    ADPCSBA͕͓͢͢ΊͰ͢
    #VJMEJOH$-*UPPMT
    

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22. ©2019 Wantedly, Inc.
    Why `pflag` and `cobra`?
    ·Α͍ͬͯΔͱ͖ͷ͓͢͢Ίબఆ
    ‣ ADPCSBAͷϑϥάύʔα͸AQqBHAͰ࣮૷͞Ε͍ͯΔ
    ͋ͱ͔ΒʮαϒίϚϯυ͕΄͍͠ʂʯͱ͍͏ͱ͖ʹADPCSBAಋೖ͕؆୯
    ࠷ॳͷٕज़બఆ
    HJUIVCDPNTQGDPCSB
    

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23. ©2019 Wantedly, Inc.
    Why `pflag` and `cobra`?
    ·Α͍ͬͯΔͱ͖ͷ͓͢͢Ίબఆ
    ‣ ADPCSBAͷϑϥάύʔα͸AQqBHAͰ࣮૷͞Ε͍ͯΔ
    ͋ͱ͔ΒʮαϒίϚϯυ͕΄͍͠ʂʯͱ͍͏ͱ͖ʹADPCSBAಋೖ͕؆୯
    ‣ ઃఆϑΝΠϧɾ؀ڥม਺ಡΈग़͠ʹศརͳύοέʔδͰ͋ΔAWJQFSAͱAQqBHAͷ૬ੑ͕ྑ͍
    ͋ͱ͔ΒʮઃఆϑΝΠϧ΄͍͠ʂʯͳΜͯ͜ͱ͸Α͋͘Δ
    AWJQFSAʹ͍ͭͯ͸ޙड़͠·͢
    ࠷ॳͷٕज़બఆ
    HJUIVCDPNTQGDPCSB
    

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24. ©2019 Wantedly, Inc.
    Directory(package) structure
    ·Α͍ͬͯΔͱ͖ͷ͓͢͢Ίύοέʔδߏ੒
    ‣ ADNEBQQOBNFAʹNBJOΛஔ͍͍ͯΔέʔεΛΑ͘ݟΔ
    FHNPCZNPCZ LVCFSOFUFT QSPNFUIFVT (PPHMF$MPVE1MBUGPSNLBOJLP
    ‣ ෳ਺όΠφϦΛు͖͍ͨͱ͖ʹରԠͰ͖Δ
    ‣ ϝΠϯͷΞϓϦέʔγϣϯίʔυ͸ʮQLHҎԼʹஔ͘ʯʮϧʔτʹஔ͘ʯ
    ͷύλʔϯΛΑ͘ݟΔ
    #VJMEJOH$-*UPPMT
    ├── cmd
    │ └──
    │ └── main.go
    ├── go.mod
    ├── go.sum
    └── pkg
    └──
    └── **/*.go
    ├── cmd
    │ └──
    │ └── main.go
    ├── go.mod
    ├── go.sum
    └── */**.go
    

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25. ©2019 Wantedly, Inc.
    Configuration
    Section subhead
    

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26. ©2019 Wantedly, Inc.
    ‣ ϢʔβʹແବͳೖྗΛͤͨ͘͞ͳ͍
    ‣ ҰํͰɺσϑΥϧτͰશͯͷχʔζʹ౴͑Δͷ͸ϜϦ
    $POGJHVSBUJPO
    

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27. ©2019 Wantedly, Inc.
    Ͳ͔͜ΒɾͲ͏͍͏༏ઌॱҐͰઃఆΛಡΈࠐΉʁ

    ઃఆϑΝΠϧʢ)0.&ʣ ઃఆϑΝΠϧʢ18%ʣ ؀ڥม਺ ࣮ߦ࣌Φϓγϣϯ
    $POGJHVSBUJPO
    

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28. ©2019 Wantedly, Inc.
    github.com/spf13/viper
    ͳΜͰ΋Ͱ͖ΔઃఆಡΈࠐΈύοέʔδ
    ‣ ͋ΒΏΔͱ͜Ζ͔ΒઃఆΛूΊͯ͘ΕΔ
    ίϚϯυϥΠϯϑϥάʢAQqBHA AqBHAʣ
    ؀ڥม਺
    ઃఆϑΝΠϧʢ+40/ 50.- :".- )$- +BWBQSPQFSUJFTʣ
    ϦϞʔτͷઃఆʢFHFUDE $POTVMʣ
    σϑΥϧτ஋
    ‣ ಡΈऔͬͨઃఆ஋͸TUSVDUʹNBQQJOHͰ͖Δ
    $POGJHVSBUJPO
    

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29. ©2019 Wantedly, Inc.
    cobra & viper
    $POGJHVSBUJPO type Config struct {
    Port int
    Host string
    Scheme string
    User, Pass string
    }
    func main() {
    var cfg Config
    cmd := &cobra.Command{
    PersistentPreRunE: func(cmd *cobra.Command, _ []string) error {
    // env
    viper.AutomaticEnv()
    // config file
    viper.AddConfigPath(".")
    viper.AddConfigPath("$HOME")
    viper.SetConfigName(".awesomeapp")
    err := viper.ReadInConfig()
    if err != nil {
    fmt.Fprintln(os.Stderr, err)
    }
    // flags
    err = viper.BindPFlags(cmd.Flags())
    if err != nil {
    fmt.Fprintln(os.Stderr, err)
    }
    

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30. ©2019 Wantedly, Inc.
    $POGJHVSBUJPO type Config struct {
    Port int
    Host string
    Scheme string
    User, Pass string
    }
    func main() {
    var cfg Config
    cmd := &cobra.Command{
    PersistentPreRunE: func(cmd *cobra.Command, _ []string) error {
    // …
    },
    RunE: func(_ *cobra.Command, args []string) error {
    fmt.Printf("%#v\n", cfg)
    return nil
    },
    }
    cmd.PersistentFlags().IntP("port", "p", 5000, "")
    cmd.PersistentFlags().StringP("host", "o", "127.0.0.1", "")
    cmd.PersistentFlags().String("scheme", "http", "")
    cmd.PersistentFlags().String("user", "root", "")
    cmd.PersistentFlags().String("pass", "", "")
    err := cmd.Execute()
    if err != nil {
    fmt.Fprintln(os.Stderr, err)
    cobra & viper
    ‣ ઃఆ஋ΛಡΈࠐΉߏ଄ମͷఆٛ
    ‣ ίϚϯυϥΠϯϑϥάͷఆٛ
    

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31. ©2019 Wantedly, Inc.
    cobra & viper
    $POGJHVSBUJPO
    Scheme string
    User, Pass string
    }
    func main() {
    var cfg Config
    cmd := &cobra.Command{
    PersistentPreRunE: func(cmd *cobra.Command, _ []string) error {
    // env
    viper.AutomaticEnv()
    // config file
    viper.AddConfigPath(".")
    viper.AddConfigPath("$HOME")
    viper.SetConfigName(".awesomeapp")
    err := viper.ReadInConfig()
    if err != nil {
    fmt.Fprintln(os.Stderr, err)
    }
    // flags
    err = viper.BindPFlags(cmd.Flags())
    if err != nil {
    fmt.Fprintln(os.Stderr, err)
    }
    return viper.Unmarshal(&cfg)
    },
    RunE: func(_ *cobra.Command, args []string) error {
    fmt.Printf("%#v\n", cfg)
    return nil
    },
    ‣ ؀ڥม਺ͷಡΈࠐΈ
    ‣ ઃఆϑΝΠϧͷಡΈࠐΈ
    ݕࡧର৅ύεͷࢦఆ
    ‣ ࣮૷ಡΉݶΓA)0.&A͸͏·͘ղऍ͢Δ
    ϑΝΠϧ໊ʢ֦ுࢠൈ͖ʣͷࢦఆ
    ‣ ίϚϯυϥΠϯϑϥάͷόΠϯυ
    

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32. ©2019 Wantedly, Inc.
    cobra & viper
    $POGJHVSBUJPO
    Scheme string
    User, Pass string
    }
    func main() {
    var cfg Config
    cmd := &cobra.Command{
    PersistentPreRunE: func(cmd *cobra.Command, _ []string) error {
    // env
    viper.AutomaticEnv()
    // config file
    viper.AddConfigPath(".")
    viper.AddConfigPath("$HOME")
    viper.SetConfigName(".awesomeapp")
    err := viper.ReadInConfig()
    if err != nil {
    fmt.Fprintln(os.Stderr, err)
    }
    // flags
    err = viper.BindPFlags(cmd.Flags())
    if err != nil {
    fmt.Fprintln(os.Stderr, err)
    }
    return viper.Unmarshal(&cfg)
    },
    RunE: func(_ *cobra.Command, args []string) error {
    fmt.Printf("%#v\n", cfg)
    return nil
    },
    ‣ ؀ڥม਺ͷಡΈࠐΈ
    ‣ ઃఆϑΝΠϧͷಡΈࠐΈ
    ݕࡧର৅ύεͷࢦఆ
    ‣ ࣮૷ಡΉݶΓA)0.&A͸͏·͘ղऍ͢Δ
    ϑΝΠϧ໊ʢ֦ுࢠൈ͖ʣͷࢦఆ
    ‣ ίϚϯυϥΠϯϑϥάͷόΠϯυ
    :) % cat .awesomeapp.toml
    host = "localhost"
    port = 8000
    :) % USER=admin PASS=pass go run . --port 8080
    main.Config{Port:8080, Host:"localhost", Scheme:"http", User:"admin", Pass:"pass"}
    

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33. ©2019 Wantedly, Inc.
    Debuggability
    Section subhead
    

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34. ©2019 Wantedly, Inc.
    ‣ ϏϧυࡁΈόΠφϦͰόά౿ΜͩΒͲ͏͢Δʁ
    ‣ %FCVHHFS΋1SJOU%FCVH΋Ͱ͖ͳ͍ͱ੾Γ෼͚΋େม
    %FCVHHBCJMJUZ
    

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35. ©2019 Wantedly, Inc.
    ‣ ϏϧυࡁΈόΠφϦͰόά౿ΜͩΒͲ͏͢Δʁ
    ‣ %FCVHHFS΋1SJOU%FCVH΋Ͱ͖ͳ͍ͱ੾Γ෼͚΋େม
    %FCVHHBCJMJUZ
    

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36. ©2019 Wantedly, Inc.
    -v (--verbose) / --debug

    σόοάΦϓγϣϯΛͭͬͯ͘ɺ։ൃதʹ͔ͭͬͨ1SJOU%FCVH͸ͦͷ··࢒͢
    $POGJHVSBUJPO
    

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37. ©2019 Wantedly, Inc.
    ‣ W WFSCPTF
    
    */'0MFWFM͘Β͍·ͰͷϩάΛग़͢
    ‣ EFCVH
    %(MFWFM΋;͘Ίɺ͢΂ͯͷϩάΛग़͢
    %FCVHHBCJMJUZ -PHMFWFM
    

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38. ©2019 Wantedly, Inc.
    %FCVHHBCJMJUZ
    e.g. cobra & zap
    RunE: func(_ *cobra.Command, args []string) error {
    zap.L().Info("loaded config", zap.Any("config", cfg))
    return nil
    },
    }
    // ...
    var debug, verbose bool
    cobra.OnInitialize(func() {
    var zapCfg zap.Config
    switch {
    case debug:
    zapCfg = zap.NewProductionConfig()
    zapCfg.Level = zap.NewAtomicLevelAt(zapcore.DebugLevel)
    case verbose:
    zapCfg = zap.NewDevelopmentConfig()
    zapCfg.Level = zap.NewAtomicLevelAt(zapcore.InfoLevel)
    }
    zapLogger, err := zapCfg.Build()
    if err != nil {
    fmt.Fprintln(os.Stderr, err)
    return
    }
    zap.ReplaceGlobals(zapLogger)
    })
    cmd.PersistentFlags().BoolVarP(&verbose, "verbose", "v", false, "Verbose lev
    cmd.PersistentFlags().BoolVar(&debug, "debug", false, "Debug level log")
    

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39. ©2019 Wantedly, Inc.
    %FCVHHBCJMJUZ
    e.g. cobra & zap
    RunE: func(_ *cobra.Command, args []string) error {
    zap.L().Info("loaded config", zap.Any("config", cfg))
    return nil
    },
    }
    // ...
    var debug, verbose bool
    cobra.OnInitialize(func() {
    var zapCfg zap.Config
    switch {
    case debug:
    zapCfg = zap.NewProductionConfig()
    zapCfg.Level = zap.NewAtomicLevelAt(zapcore.DebugLevel)
    case verbose:
    zapCfg = zap.NewDevelopmentConfig()
    zapCfg.Level = zap.NewAtomicLevelAt(zapcore.InfoLevel)
    }
    zapLogger, err := zapCfg.Build()
    if err != nil {
    fmt.Fprintln(os.Stderr, err)
    return
    }
    zap.ReplaceGlobals(zapLogger)
    })
    cmd.PersistentFlags().BoolVarP(&verbose, "verbose", "v", false, "Verbose lev
    cmd.PersistentFlags().BoolVar(&debug, "debug", false, "Debug level log")
    ‣ ίϚϯυϥΠϯϑϥάͷఆٛ
    

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40. ©2019 Wantedly, Inc.
    %FCVHHBCJMJUZ
    e.g. cobra & zap
    RunE: func(_ *cobra.Command, args []string) error {
    zap.L().Info("loaded config", zap.Any("config", cfg))
    return nil
    },
    }
    // ...
    var debug, verbose bool
    cobra.OnInitialize(func() {
    var zapCfg zap.Config
    switch {
    case debug:
    zapCfg = zap.NewProductionConfig()
    zapCfg.Level = zap.NewAtomicLevelAt(zapcore.DebugLevel)
    case verbose:
    zapCfg = zap.NewDevelopmentConfig()
    zapCfg.Level = zap.NewAtomicLevelAt(zapcore.InfoLevel)
    }
    zapLogger, err := zapCfg.Build()
    if err != nil {
    fmt.Fprintln(os.Stderr, err)
    return
    }
    zap.ReplaceGlobals(zapLogger)
    })
    cmd.PersistentFlags().BoolVarP(&verbose, "verbose", "v", false, "Verbose lev
    cmd.PersistentFlags().BoolVar(&debug, "debug", false, "Debug level log")
    ‣ ϑϥάΛ΋ͱʹ[BQॳظԽ
    

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41. ©2019 Wantedly, Inc.
    %FCVHHBCJMJUZ
    e.g. cobra & zap
    cmd := &cobra.Command{
    PersistentPreRunE: func(cmd *cobra.Command, _ []string) error {
    // env
    zap.L().Debug("load env vars")
    viper.AutomaticEnv()
    // config file
    zap.L().Debug("load config files")
    // ...
    // flags
    zap.L().Debug("bind flags")
    // ...
    zap.L().Debug("unmarshal config")
    return viper.Unmarshal(&cfg)
    },
    RunE: func(_ *cobra.Command, args []string) error {
    zap.L().Info("loaded config", zap.Any("config", cfg))
    return nil
    },
    }
    // ...
    var debug, verbose bool
    cobra.OnInitialize(func() {
    var zapCfg zap.Config
    switch {
    ‣ ίʔυதʹద౓ʹϩάΛ࢒͢
    ‣ ϑϥάΛ༩͑ͳ͍ʢ[BQΛॳظԽ͠ͳ͍ʣͱ

    OPPQMPHHFSʹॻ͖ࠐ·ΕΔ
    Α͏͢ΔʹԿ΋͠ͳ͍
    ςετʹ΋Өڹͳ͍ͷͰɺΨϯΨϯ࢒͢΂͠
    

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42. ©2019 Wantedly, Inc.
    %FCVHHBCJMJUZ
    e.g. cobra & zap
    cmd := &cobra.Command{
    PersistentPreRunE: func(cmd *cobra.Command, _ []string) error {
    // env
    zap.L().Debug("load env vars")
    viper.AutomaticEnv()
    // config file
    zap.L().Debug("load config files")
    // ...
    // flags
    zap.L().Debug("bind flags")
    // ...
    zap.L().Debug("unmarshal config")
    return viper.Unmarshal(&cfg)
    },
    RunE: func(_ *cobra.Command, args []string) error {
    zap.L().Info("loaded config", zap.Any("config", cfg))
    return nil
    },
    }
    // ...
    var debug, verbose bool
    cobra.OnInitialize(func() {
    var zapCfg zap.Config
    switch {
    ‣ ίʔυதʹద౓ʹϩάΛ࢒͢
    ‣ ϑϥάΛ༩͑ͳ͍ʢ[BQΛॳظԽ͠ͳ͍ʣͱ

    OPPQMPHHFSʹॻ͖ࠐ·ΕΔ
    Α͏͢ΔʹԿ΋͠ͳ͍
    ςετʹ΋Өڹͳ͍ͷͰɺΨϯΨϯ࢒͢΂͠
    :) % USER=admin PASS=pass go run . --port 8080 -v
    2019-05-20T06:24:57.227+0900 INFO awesomeapp/main.go:50 loaded config {"config": {"Port":
    8080,"Host":"localhost","Scheme":"http","User":"admin","Pass":"pass"}}
    :) % USER=admin PASS=pass go run . --port 8080 --debug
    {"level":"debug","ts":1558301103.629214,"caller":"awesomeapp/main.go:26","msg":"load env vars"}
    {"level":"debug","ts":1558301103.629287,"caller":"awesomeapp/main.go:30","msg":"load config files"}
    {"level":"debug","ts":1558301103.63246,"caller":"awesomeapp/main.go:40","msg":"bind flags"}
    {"level":"debug","ts":1558301103.632509,"caller":"awesomeapp/main.go:46","msg":"unmarshal config"}
    {"level":"info","ts":1558301103.632673,"caller":"awesomeapp/main.go:50","msg":"loaded config","config":{"Port":
    8080,"Host":"localhost","Scheme":"http","User":"admin","Pass":"pass"}}
    

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43. ©2019 Wantedly, Inc.
    Testability
    Section subhead
    

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44. ©2019 Wantedly, Inc.
    5FTUBCJMJUZ
    Design & Test I/O
    ӜGNU1SJOUMO
    זו׾׉ךתתⵃ欽ׅ׷ךכ
    5FTUBCMFהכ鎉ְꨇְ
    ӜJP8SJUFSזוח⣛㶷ׇׁ׷
    Ӝ刿ח䗳銲ח䘔ׄג*0ח㼎׃גJOUFSGBDF׾㐣תׇ׷
    Design I/O
    *0·ΘΓ͸(P$PO4QSJOH8FXBOU"8&40.&$-*UPPMEFWFMPQNFOUʹͯૉ੖Β͍͠঺հ͕
    IUUQTTQFBLFSEFDLDPNNJDOODJNXFXBOUBXFTPNFDMJUPPMBOEEFWFMPQNFOU
    

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45. ©2019 Wantedly, Inc.
    $-*ͷςετͷπϥϛςετͮ͠Β͍ೖग़ྗ͕ଟ͍
    ‣ FHผͷ$-*ͷXSBQQFS
    ‣ Ҿ਺͕ଟ͍ɾ௕͍ͱ୯७ʹॻ͘ͷ͕ΊΜͲ͍͘͞
    ‣ FHίʔυδΣωϨʔλ
    ‣ JNQPSUͷॱ൪΍ϑΥʔϚοτͰফ໣͢Δ
    ‣ ੜ੒෺͕ଟ͍ͱ*0ΛGBLFʹ͢Δςετ΋େม
    5FTUBCJMJUZ
    

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46. ©2019 Wantedly, Inc.
    $-*ͷςετͷπϥϛςετͮ͠Β͍ೖग़ྗ͕ଟ͍
    ‣ FHผͷ$-*ͷXSBQQFS
    ‣ Ҿ਺͕ଟ͍ɾ௕͍ͱ୯७ʹॻ͘ͷ͕ΊΜͲ͍͘͞
    ‣ FHίʔυδΣωϨʔλ
    ‣ JNQPSUͷॱ൪΍ϑΥʔϚοτͰফ໣͢Δ
    ‣ ੜ੒෺͕ଟ͍ͱ*0ΛGBLFʹ͢Δςετ΋େม
    5FTUBCJMJUZ
    'JMFTZTUFN͝ͱGBLFʹͰ͖Ε͹ָͳͷͰ͸ʁ
    

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47. ©2019 Wantedly, Inc.
    github.com/spf13/afero
    "'JMF4ZTUFN"CTUSBDUJPO4ZTUFNGPS(P
    5FTUBCJMJUZ
    type Fs interface {
    Create(name string) (File, error)
    Mkdir(name string, perm os.FileMode) error
    MkdirAll(path string, perm os.FileMode) error
    Open(name string) (File, error)
    OpenFile(name string, flag int, perm os.FileMode) (File, error)
    Remove(name string) error
    RemoveAll(path string) error
    Rename(oldname, newname string) error
    Stat(name string) (os.FileInfo, error)
    Name() string
    Chmod(name string, mode os.FileMode) error
    Chtimes(name string, atime time.Time, mtime time.Time) error
    }
    func DirExists(fs Fs, path string) (bool, error)
    func Exists(fs Fs, path string) (bool, error)
    func Glob(fs Fs, pattern string) (matches []string, err error)
    func ReadDir(fs Fs, dirname string) ([]os.FileInfo, error)
    func ReadFile(fs Fs, filename string) ([]byte, error)
    func TempDir(fs Fs, dir, prefix string) (name string, err error)
    func Walk(fs Fs, root string, walkFn filepath.WalkFunc) error
    func WriteFile(fs Fs, filename string, data []byte, perm os.FileMode) error
    `os` ΍ `io/ioutil ` ͷ
    ϑΝΠϧೖग़ྗܥʹ͋Γͦ͏ͳϝιουɾؔ਺܈
    

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48. ©2019 Wantedly, Inc.
    github.com/spf13/afero
    "'JMF4ZTUFN"CTUSBDUJPO4ZTUFNGPS(P
    5FTUBCJMJUZ
    type Fs interface {
    Create(name string) (File, error)
    Mkdir(name string, perm os.FileMode) error
    MkdirAll(path string, perm os.FileMode) error
    Open(name string) (File, error)
    OpenFile(name string, flag int, perm os.FileMode) (File, error)
    Remove(name string) error
    RemoveAll(path string) error
    Rename(oldname, newname string) error
    Stat(name string) (os.FileInfo, error)
    Name() string
    Chmod(name string, mode os.FileMode) error
    Chtimes(name string, atime time.Time, mtime time.Time) error
    }
    func DirExists(fs Fs, path string) (bool, error)
    func Exists(fs Fs, path string) (bool, error)
    func Glob(fs Fs, pattern string) (matches []string, err error)
    func ReadDir(fs Fs, dirname string) ([]os.FileInfo, error)
    func ReadFile(fs Fs, filename string) ([]byte, error)
    func TempDir(fs Fs, dir, prefix string) (name string, err error)
    func Walk(fs Fs, root string, walkFn filepath.WalkFunc) error
    func WriteFile(fs Fs, filename string, data []byte, perm os.FileMode) error
    `os` ΍ `io/ioutil ` ͷ
    ϑΝΠϧೖग़ྗܥʹ͋Γͦ͏ͳϝιουɾؔ਺܈
    

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49. ©2019 Wantedly, Inc.
    github.com/spf13/afero
    "'JMF4ZTUFN"CTUSBDUJPO4ZTUFNGPS(P
    5FTUBCJMJUZ
    func NewBasePathFs(source Fs, path string) Fs
    func NewCacheOnReadFs(base Fs, layer Fs, cacheTime time.Duration) Fs
    func NewCopyOnWriteFs(base Fs, layer Fs) Fs
    func NewMemMapFs() Fs
    func NewOsFs() Fs
    func NewReadOnlyFs(source Fs) Fs
    func NewRegexpFs(source Fs, re *regexp.Regexp) Fs
    ͍Ζ͍Ζͳ `afero.Fs` ͷίϯετϥΫλ
    

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50. ©2019 Wantedly, Inc.
    github.com/spf13/afero
    "'JMF4ZTUFN"CTUSBDUJPO4ZTUFNGPS(P
    5FTUBCJMJUZ
    func NewBasePathFs(source Fs, path string) Fs
    func NewCacheOnReadFs(base Fs, layer Fs, cacheTime time.Duration) Fs
    func NewCopyOnWriteFs(base Fs, layer Fs) Fs
    func NewMemMapFs() Fs
    func NewOsFs() Fs
    func NewReadOnlyFs(source Fs) Fs
    func NewRegexpFs(source Fs, re *regexp.Regexp) Fs
    ͍Ζ͍Ζͳ `afero.Fs` ͷίϯετϥΫλ
    

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51. ©2019 Wantedly, Inc.
    github.com/spf13/afero
    "'JMF4ZTUFN"CTUSBDUJPO4ZTUFNGPS(P
    5FTUBCJMJUZ
    func NewBasePathFs(source Fs, path string) Fs
    func NewCacheOnReadFs(base Fs, layer Fs, cacheTime time.Duration) Fs
    func NewCopyOnWriteFs(base Fs, layer Fs) Fs
    func NewMemMapFs() Fs
    func NewOsFs() Fs
    func NewReadOnlyFs(source Fs) Fs
    func NewRegexpFs(source Fs, re *regexp.Regexp) Fs
    ͍Ζ͍Ζͳ `afero.Fs` ͷίϯετϥΫλ
    ‣ A/FX0T'T
    A
    ;ͭ͏ʹ04ͷpMFTZTUFNʹॻ͖ࠐΉ࣮૷
    ΞϓϦέʔγϣϯίʔυͰ͸͜ΕΛ࢖͏
    ‣ A/FX.FN.BQ'T
    A
    ϑΝΠϧʹॻ͖ࠐΉϑϦΛͯ͠ΠϯϝϞϦͰอ࣋͢Δ
    *0͕ൃੜ͠ͳ͍ͨΊߴ଎ͰɺฒྻςετͰ΋ίϯϑϦΫτ͠ͳ͍
    ςετίʔυͰ࢖͏
    

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52. ©2019 Wantedly, Inc.
    $-*ͷςετͷπϥϛςετͮ͠Β͍ೖग़ྗ͕ଟ͍
    ‣ FHผͷ$-*ͷXSBQQFS
    ‣ Ҿ਺͕ଟ͍ɾ௕͍ͱ୯७ʹॻ͘ͷ͕ΊΜͲ͍͘͞
    ‣ FHίʔυδΣωϨʔλ
    ‣ JNQPSUͷॱ൪΍ϑΥʔϚοτͰফ໣͢Δ
    ‣ ੜ੒෺͕ଟ͍ͱ*0ΛGBLFʹ͢Δςετ΋େม
    5FTUBCJMJUZ
    ग़ྗ͕ڊେͩͬͨΓෳࡶͩͬͨΓ͢Δܥ
    (PMEFOpMFΛखॻ͖͢Δͷ΋େมʜ
    

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53. ©2019 Wantedly, Inc.
    Snapshot testing
    HJUIVCDPNCSBEMFZKLFNQDVQBMPZ
    5FTUBCJMJUZ
    t.Run("path/to/generated_file.go", func(t *testing.T) {
    data, err := ioutil.ReadFile("path/to/generated_file.go")
    if err != nil {
    t.Fatalf("failed to read file: %v", err)
    }
    cupaloy.SnapshotT(t, string(data))
    })
    

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54. ©2019 Wantedly, Inc.
    Snapshot testing
    HJUIVCDPNCSBEMFZKLFNQDVQBMPZ
    5FTUBCJMJUZ
    t.Run("path/to/generated_file.go", func(t *testing.T) {
    data, err := ioutil.ReadFile("path/to/generated_file.go")
    if err != nil {
    t.Fatalf("failed to read file: %v", err)
    }
    cupaloy.SnapshotT(t, string(data))
    })
    

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55. ©2019 Wantedly, Inc.
    Snapshot testing
    HJUIVCDPNCSBEMFZKLFNQDVQBMPZ
    5FTUBCJMJUZ
    t.Run("path/to/generated_file.go", func(t *testing.T) {
    data, err := ioutil.ReadFile("path/to/generated_file.go")
    if err != nil {
    t.Fatalf("failed to read file: %v", err)
    }
    cupaloy.SnapshotT(t, string(data))
    })
    ੜ੒͞ΕͨAHFOFSBUFE@pMFHPAΛಡΈग़͠ɺεφοϓγϣοτΛͱΔ
    εφοϓγϣοτϑΝΠϧ͕ଘࡏ͠ͳ͍৔߹
    ATOBQTIPUTUFTUOBNFAʹ৽͍͠εφοϓγϣοτΛอଘ
    εφοϓγϣοτϑΝΠϧ͕ଘࡏ͢Δ৔߹
    طଘͷεφοϓγϣοτͱൺֱ͠ɺ

    ҟͳ͍ͬͯΕ͹EJGGΛදࣔ͠ςετΛ'"*-ͤ͞Δ
    A61%"5&@4/"14)054A͕ఆٛ͞Ε͍ͯΕ͹ɺ

    εφοϓγϣοτΛߋ৽͢Δ
    

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56. ©2019 Wantedly, Inc.
    Snapshot testing
    HJUIVCDPNCSBEMFZKLFNQDVQBMPZ
    5FTUBCJMJUZ
    t.Run("path/to/generated_file.go", func(t *testing.T) {
    data, err := ioutil.ReadFile("path/to/generated_file.go")
    if err != nil {
    t.Fatalf("failed to read file: %v", err)
    }
    cupaloy.SnapshotT(t, string(data))
    })
    ੜ੒͞ΕͨAHFOFSBUFE@pMFHPAΛಡΈग़͠ɺεφοϓγϣοτΛͱΔ
    εφοϓγϣοτϑΝΠϧ͕ଘࡏ͠ͳ͍৔߹
    ATOBQTIPUTUFTUOBNFAʹ৽͍͠εφοϓγϣοτΛอଘ
    εφοϓγϣοτϑΝΠϧ͕ଘࡏ͢Δ৔߹
    طଘͷεφοϓγϣοτͱൺֱ͠ɺ

    ҟͳ͍ͬͯΕ͹EJGGΛදࣔ͠ςετΛ'"*-ͤ͞Δ
    A61%"5&@4/"14)054A͕ఆٛ͞Ε͍ͯΕ͹ɺ

    εφοϓγϣοτΛߋ৽͢Δ
    ςετͷॳճ࣮ߦ࣌ͷ݁Ռ͔ΒHPMEFOpMFΛੜ੒ͯ͘͠ΕΔ
    ճ໨Ҡߦ͸TOBQTIPUͷEJGGΛݟͭͭɺదٓߋ৽͍ͯ͘͠
    

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57. ©2019 Wantedly, Inc.
    5FTUBCJMJUZ
    fs := afero.NewMemMapFs() // テストでは OS のファイルシステムではなくメモリに書き込む
    err := NewGenerator(fs).Generate("path/to/generated_file.go")
    if err != nil {
    t.Fatalf("returned %v, want nil", err)
    }
    // ioutil ではなく afero から読み出す
    data, err := afero.ReadFile(fs, "path/to/generated_file.go")
    if err != nil {
    t.Fatalf("failed to read file: %v", err)
    }
    cupaloy.SnapshotT(t, string(data))
    afero × snapshot testing (cupaloy)
    

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58. ©2019 Wantedly, Inc.
    Viper × afero
    5FTUBCJMJUZ
    func SetFs(fs afero.Fs)
    func (v *Viper) SetFs(fs afero.Fs)
    Viper ͕ࢀর͢ΔϑΝΠϧγεςϜ΋ `afero.Fs` ͳͷͰɺ
    ͜ΕΛࠩ͠ସ͑ͯઃఆϑΝΠϧಡΈࠐΈͷςετΛ͢Δ͜ͱ΋ग़དྷ·͢
    

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59. ©2019 Wantedly, Inc.
    ‣ ໨తɾঢ়گʹ͋ͬͨύοέʔδɾϑϨʔϜϫʔΫબ୒Λ৺͕͚Α͏
    ·ΑͬͨΒATQGDPCSBAͰؒҧ͍͸গͳ͍͸ͣ
    ‣ ઃఆϑΝΠϧɾ؀ڥม਺ͷಡΈࠐΈʹ͸ATQGWJQFSAΛ૊Έ߹ΘͤΔͱศར
    ઃఆͷ༏ઌॱҐ෇͚΍TUSVDU΁ͷϚοϐϯά·Ͱ΋΍ͬͯ͘ΕΔ
    ‣ ϏϧυޙͰ΋໰୊ͷ੾Γ෼͚͕Ͱ͖ΔΑ͏ʹɺσόοάΦϓγϣϯΛ͚ͭͯ1SJOU%FCVH͠·͘Ζ͏
    Ϣʔβʹͱͬͯ΋໰୊ղܾͷॿ͚ʹͳΔ
    ใࠂ΋ͯ͠΋Β͍΍͍͢
    ‣ ϑΝΠϧγεςϜ͕བྷΉͱ͖͸ɺATQGBGFSPAΛ࢖ͬͯந৅Խ͢Δ͜ͱΛݕ౼͠Α͏
    APT'JMFA͸΋ͪΖΜͷ͜ͱɺAJP3FBEFSAͱAJP8SJUFSAͷGBLFΛͭ͘ΔΑΓ΋΋͏ҰஈམͰ͖Δ
    ίʔυੜ੒౳Λ࣮૷͢Δ༧ఆ͕͋ΔͳΒTOBQTIPUUFTUJOH΋Φεεϝ
    

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