Merge pull request #13 from Syuparn/versioning

add -v option

main.go

@@ -12,15 +12,21 @@ import (
 )
 
 var (
-	fileName   = flag.String("f", "", "use template file")
-	runsREPL   = flag.Bool("i", false, "run interactive REPL instead")
-	leftDelim  = flag.String("ldelim", "{{", "specify left deliminater")
-	rightDelim = flag.String("rdelim", "}}", "specify right deliminater")
+	fileName     = flag.String("f", "", "use template file")
+	runsREPL     = flag.Bool("i", false, "run interactive REPL instead")
+	showsVersion = flag.Bool("v", false, "show version")
+	leftDelim    = flag.String("ldelim", "{{", "specify left deliminater")
+	rightDelim   = flag.String("rdelim", "}}", "specify right deliminater")
 )
 
 func main() {
 	flag.Parse()
 
+	if *showsVersion {
+		fmt.Println(versionStr())
+		return
+	}
+
 	tmpl := newTemplate(*leftDelim, *rightDelim)
 
 	if *runsREPL {

version.go

@@ -0,0 +1,25 @@
+package main
+
+import (
+	"runtime/debug"
+)
+
+const defaultVersion = "development"
+
+var version = ""
+
+func versionStr() string {
+	// 1. if version is set (by goreleaser for example), show it
+	if version != "" {
+		return version
+	}
+
+	// 2. if runtime version is set (by go get for example), show it
+	info, ok := debug.ReadBuildInfo()
+	if ok {
+		return info.Main.Version
+	}
+
+	// 3. show default version
+	return defaultVersion
+}