add command line parser

args/args.go

@@ -0,0 +1,14 @@
+package args
+
+import (
+	"gopkg.in/alecthomas/kingpin.v2"
+)
+
+var (
+	Outfile   = kingpin.Flag("output", "The output file. Default is .gitignore and use - for stdout.").Default(".gitignore").String()
+	Templates = kingpin.Arg("templates", "Gitignore templates").Required().Strings()
+)
+
+func Parse() {
+	kingpin.Parse()
+}

go.mod

@@ -2,4 +2,9 @@ module gitignore
 
 go 1.16
 
-require github.com/sahilm/fuzzy v0.1.0 // indirect
+require (
+	github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751 // indirect
+	github.com/alecthomas/units v0.0.0-20210927113745-59d0afb8317a // indirect
+	github.com/sahilm/fuzzy v0.1.0 // indirect
+	gopkg.in/alecthomas/kingpin.v2 v2.2.6 // indirect
+)

go.sum

@@ -1,2 +1,14 @@
+github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751 h1:JYp7IbQjafoB+tBA3gMyHYHrpOtNuDiK/uB5uXxq5wM=
+github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
+github.com/alecthomas/units v0.0.0-20210927113745-59d0afb8317a h1:E/8AP5dFtMhl5KPJz66Kt9G0n+7Sn41Fy1wv9/jHOrc=
+github.com/alecthomas/units v0.0.0-20210927113745-59d0afb8317a/go.mod h1:OMCwj8VM1Kc9e19TLln2VL61YJF0x1XFtfdL4JdbSyE=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/sahilm/fuzzy v0.1.0 h1:FzWGaw2Opqyu+794ZQ9SYifWv2EIXpwP4q8dY1kDAwI=
 github.com/sahilm/fuzzy v0.1.0/go.mod h1:VFvziUEIMCrT6A6tw2RFIXPXXmzXbOsSHF0DOI8ZK9Y=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
+gopkg.in/alecthomas/kingpin.v2 v2.2.6 h1:jMFz6MfLP0/4fUyZle81rXUoxOBFi19VUFKVDOQfozc=
+gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLkstjWtayDeSgw=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"embed"
 	"fmt"
+	"gitignore/args"
 	"io/fs"
 	"io/ioutil"
 	"os"
@@ -80,9 +81,9 @@ func fuzzyMatch(arg string, all IgnoreFiles) *IgnoreFile {
 }
 
 func main() {
-	args := os.Args[1:]
+	args.Parse()
 	matches := []string{}
-	for _, arg := range args {
+	for _, arg := range *args.Templates {
 		f := fuzzyMatch(arg, getAllIgnores())
 		if f == nil {
 			continue
@@ -93,6 +94,11 @@ func main() {
 		fmt.Fprintf(os.Stderr, "No gitignore template found.\n")
 		return
 	}
-	fmt.Printf("Gitignore of [%s] writes to .gitignore file.\n", strings.Join(matches, ", "))
-	ioutil.WriteFile(".gitignore", []byte(gitignore(matches)), 0666)
+	output := strings.TrimSpace(*args.Outfile)
+	if output == "-" {
+		fmt.Println(gitignore(matches))
+		return
+	}
+	fmt.Printf("Gitignore of [%s] writes to %s file.\n", strings.Join(matches, ", "), output)
+	ioutil.WriteFile(output, []byte(gitignore(matches)), 0666)
 }