find() looks for flag's default values only when requested.

Default value should be looked for by Get(), but not by IsSet().

This logic should remain inside find(), to make sure that shadowing
of keys is handled properly.

Fixes Issue #276.

viper.go

@@ -612,7 +612,7 @@ func GetViper() *Viper {
 func Get(key string) interface{} { return v.Get(key) }
 func (v *Viper) Get(key string) interface{} {
 	lcaseKey := strings.ToLower(key)
-	val := v.find(lcaseKey)
+	val := v.find(lcaseKey, true)
 	if val == nil {
 		return nil
 	}
@@ -877,11 +877,15 @@ func (v *Viper) BindEnv(input ...string) error {
 }
 
 // Given a key, find the value.
-// Viper will check in the following order:
-// flag, env, config file, key/value store, default.
+//
 // Viper will check to see if an alias exists first.
+// Viper will then check in the following order:
+// flag, env, config file, key/value store.
+// Lastly, if no value was found and flagDefault is true, and if the key
+// corresponds to a flag, the flag's default value is returned.
+//
 // Note: this assumes a lower-cased key given.
-func (v *Viper) find(lcaseKey string) interface{} {
+func (v *Viper) find(lcaseKey string, flagDefault bool) interface{} {
 
 	var (
 		val    interface{}
@@ -978,24 +982,26 @@ func (v *Viper) find(lcaseKey string) interface{} {
 		return nil
 	}
 
-	// last chance: if no other value is returned and a flag does exist for the value,
-	// get the flag's value even if the flag's value has not changed
-	if flag, exists := v.pflags[lcaseKey]; exists {
-		switch flag.ValueType() {
-		case "int", "int8", "int16", "int32", "int64":
-			return cast.ToInt(flag.ValueString())
-		case "bool":
-			return cast.ToBool(flag.ValueString())
-		case "stringSlice":
-			s := strings.TrimPrefix(flag.ValueString(), "[")
-			s = strings.TrimSuffix(s, "]")
-			res, _ := readAsCSV(s)
-			return res
-		default:
-			return flag.ValueString()
+	if flagDefault {
+		// last chance: if no value is found and a flag does exist for the key,
+		// get the flag's default value even if the flag's value has not been set.
+		if flag, exists := v.pflags[lcaseKey]; exists {
+			switch flag.ValueType() {
+			case "int", "int8", "int16", "int32", "int64":
+				return cast.ToInt(flag.ValueString())
+			case "bool":
+				return cast.ToBool(flag.ValueString())
+			case "stringSlice":
+				s := strings.TrimPrefix(flag.ValueString(), "[")
+				s = strings.TrimSuffix(s, "]")
+				res, _ := readAsCSV(s)
+				return res
+			default:
+				return flag.ValueString()
+			}
 		}
+		// last item, no need to check shadowing
 	}
-	// last item, no need to check shadowing
 
 	return nil
 }
@@ -1014,7 +1020,7 @@ func readAsCSV(val string) ([]string, error) {
 func IsSet(key string) bool { return v.IsSet(key) }
 func (v *Viper) IsSet(key string) bool {
 	lcaseKey := strings.ToLower(key)
-	val := v.find(lcaseKey)
+	val := v.find(lcaseKey, false)
 	return val != nil
 }