revisiting the idea after a fair amount of usage

.travis.yml

@@ -1,10 +1,9 @@
 language: go
 go:
-  - 1.1
-  - 1.2
-  - 1.3
-  - 1.4
-  - 1.5
+  - 1.9
+  - "1.10"
+  - 1.11
+  - 1.12
   - tip
 before_install:
   - go get -v github.com/smartystreets/goconvey

doc.go

@@ -1,91 +1,5 @@
 /*Package onion is a layer based, pluggable config manager for golang.
-
-Layers
-
-Each config object can has more than one config layer. currently there is 3 layer
-type is supported.
-
-Default layer
-
-This layer is special layer to set default for configs. usage is simple :
-
-    l := onion.NewDefaultLayer()
-    l.SetDefault("my.daughter.name", "bita")
-
-This layer must be added before all other layer, and defaults must be added before adding it to onion
-
-File layer
-
-File layer is the basic one.
-
-    l := onion.NewFileLayer("/path/to/the/file.ext")
-
-the onion package only support for json extension by itself, and there is toml
-and yaml loader available as sub package for this one.
-
-Also writing a new loader is very easy, just implement the FileLoader interface
-and call the RegisterLoader function with your loader object
-
-Folder layer
-
-Folder layer is much like file layer but it get a folder and search for the
-first file with tha specific name and supported extension
-
-    l := onion.NewFolderLayer("/path/to/folder", "filename")
-
-the file name part is WHITOUT extension. library check for supported loader
-extension in that folder and return the first one.
-
-ENV layer
-
-The other layer is env layer. this layer accept a whitelist of env variables
-and use them as value .
-
-    l := onion.NewEnvLayer("PORT", "STATIC_ROOT", "NEXT")
-
-this layer currently dose not support nested variables.
-
-YOUR layer
-
-Just implement the onion.Layer interface!
-
-Getting from config
-
-After adding layers to config, its easy to get the config values.
-
-    o := onion.New()
-    o.AddLayer(l1)
-    o.AddLayer(l2)
-
-    o.GetString("key", "default")
-    o.GetBool("anotherkey", true)
-
-    o.GetInt("worker.count", 10) // Nested value
-
-library also support for mapping data to a structure. define your structure :
-
-    type MyStruct struct {
-        Key1 string
-        Key2 int
-
-        Key3 bool `onion:"boolkey"`  // struct tag is supported to change the name
-
-        Other struct {
-            Nested string
-        }
-    }
-
-    o := onion.New()
-    // Add layers.....
-    c := MyStruct{}
-    o.GetStruct("prefix", &c)
-
-the the c.Key1 is equal to o.GetStringDefault("prefix.key1", c.Key1) , note that the
-value before calling this function is used as default value, when the type is
-not matched or the value is not exists, the the default is returned
-For changing the key name, struct tag is supported. for example in the above
-example c.Key3 is equal to o.GetBoolDefault("prefix.boolkey", c.Key3)
-
-Also nested struct (and embeded ones) are supported too.
+The goal is to have multiple layer and load value base on this layers. the first layer with the response
+is used to provide the response.
 */
 package onion

env_layer.go

@@ -5,30 +5,14 @@ import (
 	"strings"
 )
 
-//TODO : support for nested value (maybe?)
-type envLoader struct {
-	whiteList []string
-
-	loaded bool
-	data   map[string]interface{}
-}
-
-func (el *envLoader) Load() (map[string]interface{}, error) {
-	if el.loaded {
-		return el.data, nil
-	}
-	for _, env := range el.whiteList {
-		v := os.Getenv(strings.ToUpper(env))
-		if v != "" {
-			el.data[env] = v
+// NewEnvLayer create new layer using the whitelist of environment values.
+func NewEnvLayer(separator string, whiteList ...string) Layer {
+	data := make(map[string]interface{})
+	for i := range whiteList {
+		if s := os.Getenv(whiteList[i]); s != "" {
+			data[strings.ToLower(whiteList[i])] = s
 		}
 	}
-	el.loaded = true
-	return el.data, nil
-}
 
-// NewEnvLayer create a environment loader. this loader accept a whitelist of allowed variables
-// TODO : find a way to map env variable with different name
-func NewEnvLayer(whiteList ...string) Layer {
-	return &envLoader{whiteList, false, make(map[string]interface{})}
+	return NewMapLayerSeparator(data, separator)
 }