Add support for parsing multiple config files

Author: fkollmann

README.md

@@ -1,5 +1,6 @@
 # smartpricer/flag
 
+- Add support for multiple config files (separated by colon `:`)
 - Add support for yaml-like config file format
 - Change config file to support environment variable-style flag names
 

extras_test.go

@@ -200,6 +200,35 @@ func TestDefaultConfigFlagnameYAML(t *testing.T) {
 	}
 }
 
+func TestDefaultConfigFlagnameMultiple(t *testing.T) {
+	f := NewFlagSet("test", ContinueOnError)
+
+	f.Bool("bool", false, "bool value")
+	f.Bool("bool2", false, "bool2 value")
+	f.Int("int", 0, "int value")
+	f.Int64("int64", 0, "int64 value")
+	f.Uint("uint", 0, "uint value")
+	f.Uint64("uint64", 0, "uint64 value")
+	stringFlag := f.String("string", "0", "string value")
+	f.String("string2", "0", "string value")
+	f.String("string3-env-like", "0", "string value")
+	f.Float64("float64", 0, "float64 value")
+	f.Duration("duration", 5*time.Second, "time.Duration value")
+
+	f.String(DefaultConfigFlagname, "./testdata/test.yml:./testdata/test.conf", "config path")
+
+	if err := os.Unsetenv("STRING"); err != nil {
+		t.Error(err)
+	}
+
+	if err := f.Parse([]string{}); err != nil {
+		t.Error("parse failed; ", err)
+	}
+
+	if *stringFlag != "helloYAML" {
+		t.Error("string flag should be `hello`, is", *stringFlag)
+	}
+}
 
 func TestDefaultConfigFlagnameMissingFile(t *testing.T) {
 	f := NewFlagSet("test", ContinueOnError)

flag.go

@@ -1225,19 +1225,23 @@ func (f *FlagSet) parseExtras() error {
 		cFile = cf.Value.String()
 	}
 	if cFile != "" {
-		if err := f.ParseFile(cFile); err != nil {
-			switch f.errorHandling {
-			case ContinueOnError:
-				return err
-			case ExitOnError:
-				if err == ErrHelp {
-					os.Exit(0)
+		singleFiles := strings.Split(cFile, ":")
+
+		for _, singleFile := range singleFiles {
+			if err := f.ParseFile(singleFile); err != nil {
+				switch f.errorHandling {
+				case ContinueOnError:
+					return err
+				case ExitOnError:
+					if err == ErrHelp {
+						os.Exit(0)
+					}
+					os.Exit(2)
+				case PanicOnError:
+					panic(err)
 				}
-				os.Exit(2)
-			case PanicOnError:
-				panic(err)
+				return err
 			}
-			return err
 		}
 	}
 	// /* jnovack/flag END */