Flags support to define templates

main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"errors"
+	"flag"
 	"fmt"
 	"io"
 	"os"
@@ -11,8 +12,7 @@ import (
 const (
 	templateGlob = "*.tmpl"
 	exitFail     = 1
-	usage        = `Quick Usage: fvv <template definition name>
-
+	usageFooter  = `
 Fusozay Var Var is a CLI application for quickly rendering out text templates.
 I often write outfit and character descriptions that reuses a lot of elements.
 This allows me to DRY up my descriptions and still quickly get results.
@@ -20,11 +20,10 @@ This allows me to DRY up my descriptions and still quickly get results.
 Template requirements:
 - All of the templates must be valid golang templates.
 - They must not require any variables to be passed in.
-- All templates must have the '.tmpl' extension. All other files ignored.
 - The template you want to render must be "named"
 https://golang.org/pkg/text/template/#hdr-Nested_template_definitions
 
-Version 1.0.0
+Version 1.2.0
 `
 )
 
@@ -36,16 +35,32 @@ func main() {
 }
 
 func run(args []string, fileGlob string, stdout io.Writer) error {
-	if len(args) < 2 {
-		return errors.New(usage)
+	flags := flag.NewFlagSet(args[0], flag.ContinueOnError)
+	flags.Usage = func() {
+		fmt.Fprintf(flags.Output(), "Quick Usage: %s <template definition name>\n", args[0])
+		flags.PrintDefaults()
+		fmt.Fprint(flags.Output(), usageFooter)
+	}
+	var (
+		glob = flags.String("t", fileGlob, "glob to use to find templates")
+	)
+	if err := flags.Parse(args[1:]); err != nil {
+		return err
 	}
 
-	tmpl, err := template.ParseGlob(fileGlob)
+	if flags.NArg() != 1 {
+		flags.Usage()
+		return errors.New("template definition missing")
+	}
+	nonFlagArg := flags.Args()[0]
+
+
+	tmpl, err := template.ParseGlob(*glob)
 	if err != nil {
 		return fmt.Errorf("checking for templates: %v", err)
 	}
 
-	err = tmpl.ExecuteTemplate(stdout, args[1], "no data needed")
+	err = tmpl.ExecuteTemplate(stdout, nonFlagArg, "no data needed")
 	if err != nil {
 		return fmt.Errorf("executing template %s: %v", args[1], err)
 	}

main_test.go

@@ -5,7 +5,7 @@ import (
 	"testing"
 )
 
-func Test_run(t *testing.T) {
+func TestRun(t *testing.T) {
 	type args struct {
 		args     []string
 		fileGlob string
@@ -20,6 +20,8 @@ func Test_run(t *testing.T) {
 		{"missing template", args{[]string{"fvv", "t3"}, "*.tmpl"}, "", true},
 		{"definition does not exist", args{[]string{"fvv", "t20"}, "test_files/*.tmpl"}, "", true},
 		{"happy path", args{[]string{"fvv", "T3"}, "test_files/*.tmpl"}, "ONE\nStandard stuff\nTWO", false},
+		{"flag template", args{[]string{"fvv", "-t", "test_files/*.tmpl", "T3"}, "*.tmpl"}, "ONE\nStandard stuff\nTWO", false},
+		{"bad flag", args{[]string{"fvv", "-z", "test_files/*.tmpl"}, ""}, "", true},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {