Moving error handlers to the cache implementations.

cache.go

@@ -12,9 +12,9 @@ import (
 // Cache represents a token cacher.
 type Cache interface {
 	// Read reads a cache token from the specified file.
-	Read() (token *Token, err error)
+	Read() (token *Token)
 	// Write writes a token to the specified file.
-	Write(token *Token) (err error)
+	Write(token *Token)
 }
 
 // NewFileCache creates a new file cache.
@@ -24,25 +24,29 @@ func NewFileCache(filename string) *FileCache {
 
 // FileCache represents a file based token cacher.
 type FileCache struct {
-	filename string
+	filename         string
+	ErrorHandlerFunc func(error)
 }
 
 // Read reads a cache token from the specified file.
-func (f *FileCache) Read() (token *Token, err error) {
+func (f *FileCache) Read() (token *Token) {
 	data, err := ioutil.ReadFile(f.filename)
-	if err != nil {
-		return nil, err
+	if err == nil {
+		err = json.Unmarshal(data, token)
 	}
-	token = &Token{}
-	err = json.Unmarshal(data, &token)
-	return token, err
+	if f.ErrorHandlerFunc != nil {
+		f.ErrorHandlerFunc(err)
+	}
+	return
 }
 
 // Write writes a token to the specified file.
-func (f *FileCache) Write(token *Token) error {
+func (f *FileCache) Write(token *Token) {
 	data, err := json.Marshal(token)
-	if err != nil {
-		return err
+	if err == nil {
+		err = ioutil.WriteFile(f.filename, data, 0644)
+	}
+	if f.ErrorHandlerFunc != nil {
+		f.ErrorHandlerFunc(err)
 	}
-	return ioutil.WriteFile(f.filename, data, 0644)
 }