Write to tempfile first then rename

stringer.go

@@ -126,16 +126,31 @@ func main() {
 	// Format the output.
 	src := g.format()
 
-	// Write to file.
+	// Figure out filename to write to
 	outputName := *output
 	if outputName == "" {
 		baseName := fmt.Sprintf("%s_enumer.go", types[0])
 		outputName = filepath.Join(dir, strings.ToLower(baseName))
 	}
-	err := ioutil.WriteFile(outputName, src, 0644)
+
+	// Write to tmpfile first
+	tmpFile, err := ioutil.TempFile("", fmt.Sprintf("%s_enumer_", types[0]))
 	if err != nil {
+		log.Fatalf("creating temporary file for output: %s", err)
+	}
+	_, err = tmpFile.Write(src)
+	if err != nil {
+		tmpFile.Close()
+		os.Remove(tmpFile.Name())
 		log.Fatalf("writing output: %s", err)
 	}
+	tmpFile.Close()
+
+	// Rename tmpfile to output file
+	err = os.Rename(tmpFile.Name(), outputName)
+	if err != nil {
+		log.Fatalf("moving tempfile to output file: %s", err)
+	}
 }
 
 // isDirectory reports whether the named file is a directory.