Use cobra to handle command line parameters

cmd/gold/main.go

@@ -1,15 +1,31 @@
 package main
 
 import (
-	"flag"
+	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
 	"os"
 
+	"github.com/spf13/cobra"
+
 	"github.com/charmbracelet/gold"
 )
 
+var (
+	rootCmd = &cobra.Command{
+		Use:           "gold SOURCE",
+		Short:         "Render markdown on the CLI, with pizzazz!",
+		SilenceErrors: false,
+		SilenceUsage:  false,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return execute(args)
+		},
+	}
+
+	style string
+)
+
 func readerFromArgument(s string) (io.ReadCloser, error) {
 	if s == "-" {
 		return os.Stdin, nil
@@ -26,27 +42,32 @@ func readerFromArgument(s string) (io.ReadCloser, error) {
 	return os.Open(s)
 }
 
-func main() {
-	s := flag.String("s", "", "style json path")
-	flag.Parse()
-	args := flag.Args()
+func execute(args []string) error {
 	if len(args) != 1 {
-		fmt.Println("Missing Markdown file. Usage: ./gold -s STYLE.json FILE.md")
-		os.Exit(1)
+		return errors.New("missing markdown source")
 	}
 
 	in, err := readerFromArgument(args[0])
 	if err != nil {
-		fmt.Println(err)
-		os.Exit(1)
+		return err
 	}
 	defer in.Close()
 
 	b, _ := ioutil.ReadAll(in)
-	out, err := gold.RenderBytes(b, *s)
+	out, err := gold.RenderBytes(b, style)
 	if err != nil {
-		fmt.Println(err)
-		os.Exit(1)
+		return err
 	}
 	fmt.Printf("%s", string(out))
+	return nil
+}
+
+func main() {
+	if err := rootCmd.Execute(); err != nil {
+		os.Exit(-1)
+	}
+}
+
+func init() {
+	rootCmd.Flags().StringVarP(&style, "style", "s", "dark.json", "style JSON path")
 }

go.mod

@@ -5,5 +5,6 @@ go 1.13
 require (
 	github.com/logrusorgru/aurora v0.0.0-20191017060258-dc85c304c434
 	github.com/shurcooL/sanitized_anchor_name v1.0.0 // indirect
+	github.com/spf13/cobra v0.0.5
 	gopkg.in/russross/blackfriday.v2 v2.0.0
 )

go.sum

@@ -1,6 +1,38 @@
+github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
+github.com/armon/consul-api v0.0.0-20180202201655-eb2c6b5be1b6/go.mod h1:grANhF5doyWs3UAsr3K4I6qtAmlQcZDesFNEHPZAzj8=
+github.com/coreos/etcd v3.3.10+incompatible/go.mod h1:uF7uidLiAD3TWHmW31ZFd/JWoc32PjwdhPthX9715RE=
+github.com/coreos/go-etcd v2.0.0+incompatible/go.mod h1:Jez6KQU2B/sWsbdaef3ED8NzMklzPG4d5KIOhIy30Tk=
+github.com/coreos/go-semver v0.2.0/go.mod h1:nnelYz7RCh+5ahJtPPxZlU+153eP4D4r3EedlOD2RNk=
+github.com/cpuguy83/go-md2man v1.0.10/go.mod h1:SmD6nW6nTyfqj6ABTjUi3V3JVMnlJmwcJI5acqYI6dE=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
+github.com/hashicorp/hcl v1.0.0/go.mod h1:E5yfLk+7swimpb2L/Alb/PJmXilQ/rhwaUYs4T20WEQ=
+github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=
 github.com/logrusorgru/aurora v0.0.0-20191017060258-dc85c304c434 h1:im9kkmH0WWwxzegiv18gSUJbuXR9y028rXrWuPp6Jug=
 github.com/logrusorgru/aurora v0.0.0-20191017060258-dc85c304c434/go.mod h1:7rIyQOR62GCctdiQpZ/zOJlFyk6y+94wXzv6RNZgaR4=
+github.com/magiconair/properties v1.8.0/go.mod h1:PppfXfuXeibc/6YijjN8zIbojt8czPbwD3XqdrwzmxQ=
+github.com/mitchellh/go-homedir v1.1.0/go.mod h1:SfyaCUpYCn1Vlf4IUYiD9fPX4A5wJrkLzIz1N1q0pr0=
+github.com/mitchellh/mapstructure v1.1.2/go.mod h1:FVVH3fgwuzCH5S8UJGiWEs2h04kUh9fWfEaFds41c1Y=
+github.com/pelletier/go-toml v1.2.0/go.mod h1:5z9KED0ma1S8pY6P1sdut58dfprrGBbd/94hg7ilaic=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/russross/blackfriday v1.5.2/go.mod h1:JO/DiYxRf+HjHt06OyowR9PTA263kcR/rfWxYHBV53g=
 github.com/shurcooL/sanitized_anchor_name v1.0.0 h1:PdmoCO6wvbs+7yrJyMORt4/BmY5IYyJwS/kOiWx8mHo=
 github.com/shurcooL/sanitized_anchor_name v1.0.0/go.mod h1:1NzhyTcUVG4SuEtjjoZeVRXNmyL/1OwPU0+IJeTBvfc=
+github.com/spf13/afero v1.1.2/go.mod h1:j4pytiNVoe2o6bmDsKpLACNPDBIoEAkihy7loJ1B0CQ=
+github.com/spf13/cast v1.3.0/go.mod h1:Qx5cxh0v+4UWYiBimWS+eyWzqEqokIECu5etghLkUJE=
+github.com/spf13/cobra v0.0.5 h1:f0B+LkLX6DtmRH1isoNA9VTtNUK9K8xYd28JNNfOv/s=
+github.com/spf13/cobra v0.0.5/go.mod h1:3K3wKZymM7VvHMDS9+Akkh4K60UwM26emMESw8tLCHU=
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+github.com/spf13/pflag v1.0.3 h1:zPAT6CGy6wXeQ7NtTnaTerfKOsV6V6F8agHXFiazDkg=
+github.com/spf13/pflag v1.0.3/go.mod h1:DYY7MBk1bdzusC3SYhjObp+wFpr4gzcvqqNjLnInEg4=
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+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+github.com/ugorji/go/codec v0.0.0-20181204163529-d75b2dcb6bc8/go.mod h1:VFNgLljTbGfSG7qAOspJ7OScBnGdDN/yBr0sguwnwf0=
+github.com/xordataexchange/crypt v0.0.3-0.20170626215501-b2862e3d0a77/go.mod h1:aYKd//L2LvnjZzWKhF00oedf4jCCReLcmhLdhm1A27Q=
+golang.org/x/crypto v0.0.0-20181203042331-505ab145d0a9/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
+golang.org/x/sys v0.0.0-20181205085412-a5c9d58dba9a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/russross/blackfriday.v2 v2.0.0 h1:+FlnIV8DSQnT7NZ43hcVKcdJdzZoeCmJj4Ql8gq5keA=
 gopkg.in/russross/blackfriday.v2 v2.0.0/go.mod h1:6sSBNz/GtOm/pJTuh5UmBK2ZHfmnxGbl2NZg1UliSOI=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=