Stuff

README.md

@@ -31,14 +31,12 @@ import "github.com/localhots/gobelt/filecache"
 
 ```go
 ctx := context.Background()
-var val int
-filecache.Load(&val, "tmp/cache/items.json", func() interface{} {
-    var items []Item
+var items []Item
+filecache.Load(&items, "tmp/cache/items.json", func() {  
     err := conn.Query(ctx, "SELECT * FROM items").Load(&items).Error()
     if err != nil {
         log.Fatalf("Failed to load items: %v", err)
     }
-    return items
 })
 ```
 
@@ -83,6 +81,37 @@ s := setstring.New("one", "two")
 s.Add("three")
 s.Remove("one", "two").Add("four", "five")
 fmt.Println("Size:", s.Len()) // 3
-fmt.Println("Has one", s.Has("one"))
+fmt.Println("Has one", s.Has("one")) // false
 fmt.Println(s.SortedSlice()) // [three four five]
 ```
+
+### Config
+
+```go
+import "github.com/localhots/gobelt/config"
+```
+
+Describe configuration structure inside a target package.
+
+```go
+package db
+
+var conf struct {
+    Flavor string `toml:"flavor"`
+    DSN    string `toml:"dsn"`
+}
+
+func init() {
+    config.Require("db", &conf)
+}
+```
+
+Load configuration from a `main` function:
+
+```go
+package main
+
+func main() {
+    config.Load("config/config.toml")
+}
+```

config/config.go

@@ -1 +1,34 @@
 package config
+
+import (
+	"github.com/BurntSushi/toml"
+)
+
+var configs = map[string]interface{}{}
+
+// Require registers a request for package configuration.
+func Require(key string, dest interface{}) {
+	configs[key] = dest
+}
+
+// Load reads the config file and distributes provided configuration to
+// requested destinations.
+func Load(path string) error {
+	var conf map[string]toml.Primitive
+	meta, err := toml.DecodeFile(path, &conf)
+	if err != nil {
+		return err
+	}
+
+	for key, prim := range conf {
+		dest, ok := configs[key]
+		if !ok {
+			continue
+		}
+		err := meta.PrimitiveDecode(prim, dest)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}

config/config_test.go

@@ -0,0 +1,48 @@
+package config
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+func TestConfig(t *testing.T) {
+	type numbers struct {
+		Ary []int `toml:"ary"`
+		I   int   `toml:"i"`
+	}
+	var nums numbers
+	Require("numbers", &nums)
+	numsExp := numbers{
+		Ary: []int{1, 2, 3},
+		I:   123,
+	}
+
+	type words struct {
+		Foo  string `toml:"foo"`
+		List struct {
+			Foo []string `toml:"foo"`
+		} `toml:"list"`
+	}
+	var w words
+	Require("words", &w)
+	wordsExp := words{
+		Foo: "bar",
+		List: struct {
+			Foo []string `toml:"foo"`
+		}{
+			Foo: []string{"buzz", "fizz"},
+		},
+	}
+
+	err := Load("example.toml")
+	if err != nil {
+		t.Fatalf("Failed to load config: %v", err)
+	}
+	if !cmp.Equal(numsExp, nums) {
+		t.Errorf("Numbers mismatch: %s", cmp.Diff(numsExp, nums))
+	}
+	if !cmp.Equal(wordsExp, w) {
+		t.Errorf("Words mismatch: %s", cmp.Diff(wordsExp, w))
+	}
+}

config/example.toml

@@ -0,0 +1,8 @@
+[numbers]
+ary = [1, 2, 3]
+i = 123
+
+[words]
+foo = "bar"
+[words.list]
+foo = ["buzz", "fizz"]

filecache/filecache.go

@@ -4,18 +4,15 @@ import (
 	"encoding/json"
 	"io/ioutil"
 	"os"
-	"reflect"
 )
 
 // Load will look for a given file. If it exists, it would unmarshal its
 // contents into the given value. If the file does not exist, a supplied
 // function would be called and its output would be written to a file.
-func Load(val interface{}, filename string, fn func() interface{}) error {
+func Load(val interface{}, filename string, fn func()) error {
 	_, err := os.Stat(filename)
 	if os.IsNotExist(err) {
-		out := fn()
-		reflect.ValueOf(val).Elem().Set(reflect.ValueOf(out))
-
+		fn()
 		body, err := json.Marshal(val)
 		if err != nil {
 			return err

filecache/filecache_test.go

@@ -12,9 +12,9 @@ func TestFileCache(t *testing.T) {
 	var res int
 	var nCalled int
 	for i := 0; i < 10; i++ {
-		err := Load(&res, filename, func() interface{} {
+		err := Load(&res, filename, func() {
 			nCalled++
-			return exp
+			res = exp
 		})
 		if err != nil {
 			t.Fatalf("Error occurred while loading cache: %v", err)