From 6a345d96037884881e6c32d04e509712abea4b00 Mon Sep 17 00:00:00 2001
From: "Fabrizio (Misto) Milo" <mistobaan@gmail.com>
Date: Tue, 7 Oct 2014 18:07:50 -0700
Subject: [PATCH] feature: add support for time.Duration

---
 README.md   | 11 ++++++-----
 env_test.go | 20 ++++++++++++++++++++
 var.go      | 18 ++++++++++++++++--
 3 files changed, 42 insertions(+), 7 deletions(-)
 create mode 100644 env_test.go

diff --git a/README.md b/README.md
index 84f744e..e63e149 100644
--- a/README.md
+++ b/README.md
@@ -39,16 +39,17 @@ func main() {
 ```
 
 
-This library uses runtime reflection just like `encoding/json`. Most programs won't have more than a handful of config objects, so the slowness typically associated with reflection is negligible here. 
+This library uses runtime reflection just like `encoding/json`. Most programs won't have more than a handful of config objects, so the slowness typically associated with reflection is negligible here.
 
 ### Supported types
 
-Four types are currently supported: 
+Four types are currently supported:
 
 * `string` - defaults to `""`
 * `int` - defaults to `0`
 * `bool` - defaults to `false`
-* `float64` - defaults to `0.0` 
+* `float64` - defaults to `0.0`
+* `time.Duration` - defaults to `0`
 
 Support for custom types via interfaces will likely make an an appearance at a later date.
 
@@ -85,7 +86,7 @@ type Config struct {
 
 #### `default`
 
-If specified, the default will be used if no environment variable is found matching the key. Default values must be castable to the associated struct field type, otherwise an error is returned. 
+If specified, the default will be used if no environment variable is found matching the key. Default values must be castable to the associated struct field type, otherwise an error is returned.
 
 ```go
 // Look for a variable `ENABLED` or otherwise default to true
@@ -108,7 +109,7 @@ config := &Config{}
 fmt.Println(config.Name) // prints "Inigo"
 ```
 
-#### `options` 
+#### `options`
 
 Options ensure that an environment variable is in a set of possible valid values. If it is not, an error is returned.
 
diff --git a/env_test.go b/env_test.go
new file mode 100644
index 0000000..f00ffab
--- /dev/null
+++ b/env_test.go
@@ -0,0 +1,20 @@
+package env
+
+import (
+	"testing"
+	"time"
+)
+
+func TestParseDuration(t *testing.T) {
+	var cfg = struct {
+		Duration time.Duration `env:"key=DURATION default=5s"`
+	}{}
+
+	if err := Process(&cfg); err != nil {
+		t.Fatal(err)
+	}
+
+	if cfg.Duration != time.Second*5 {
+		t.Fatalf("%v != %f ", cfg.Duration, time.Second*5)
+	}
+}
diff --git a/var.go b/var.go
index e8f6b8e..66f8f21 100644
--- a/var.go
+++ b/var.go
@@ -7,6 +7,7 @@ import (
 	_ "regexp"
 	"strconv"
 	"strings"
+	"time"
 )
 
 // Var struct
@@ -22,11 +23,16 @@ type Var struct {
 
 // NewVar returns a new Var
 func NewVar(field reflect.StructField) (*Var, error) {
+	return NewVarWithFunc(field, os.Getenv)
+}
+
+// NewVarWithFunc returns a new Var. get returns the value for the given key
+func NewVarWithFunc(field reflect.StructField, get func(string) string) (*Var, error) {
 	// spew.Dump(new(Var).Default == reflect.ValueOf(nil))
 	newVar := &Var{} //Default: reflect.ValueOf(nil)}
 	newVar.Parse(field)
 
-	value, err := convert(newVar.Type, os.Getenv(newVar.Key))
+	value, err := convert(newVar.Type, get(newVar.Key))
 	if err != nil {
 		return newVar, err
 	}
@@ -168,6 +174,15 @@ func convert(t reflect.Type, value string) (reflect.Value, error) {
 		return reflect.ValueOf(nil), nil
 	}
 
+	var d time.Duration
+
+	switch t {
+	case reflect.TypeOf(d):
+		result, err := time.ParseDuration(value)
+		return reflect.ValueOf(result), err
+	default:
+	}
+
 	switch t.Kind() {
 	case reflect.String:
 		return reflect.ValueOf(value), nil
@@ -177,7 +192,6 @@ func convert(t reflect.Type, value string) (reflect.Value, error) {
 	case reflect.Int:
 		return parseInt(value)
 	case reflect.Bool:
-
 		return parseBool(value)
 	}