--- /dev/null
+// Package env provides a convenient way to convert environment
+// variables into Go data. It is similar in design to package
+// flag.
+package env
+
+import (
+ "log"
+ "net/url"
+ "os"
+ "strconv"
+ "strings"
+ "time"
+)
+
+var funcs []func() bool
+
+// Int returns a new int pointer.
+// When Parse is called,
+// env var name will be parsed
+// and the resulting value
+// will be assigned to the returned location.
+func Int(name string, value int) *int {
+ p := new(int)
+ IntVar(p, name, value)
+ return p
+}
+
+// IntVar defines an int var with the specified
+// name and default value. The argument p points
+// to an int variable in which to store the
+// value of the environment var.
+func IntVar(p *int, name string, value int) {
+ *p = value
+ funcs = append(funcs, func() bool {
+ if s := os.Getenv(name); s != "" {
+ v, err := strconv.Atoi(s)
+ if err != nil {
+ log.Println(name, err)
+ return false
+ }
+ *p = v
+ }
+ return true
+ })
+}
+
+// Bool returns a new bool pointer.
+// When Parse is called,
+// env var name will be parsed
+// and the resulting value
+// will be assigned to the returned location.
+// Parsing uses strconv.ParseBool.
+func Bool(name string, value bool) *bool {
+ p := new(bool)
+ BoolVar(p, name, value)
+ return p
+}
+
+// BoolVar defines a bool var with the specified
+// name and default value. The argument p points
+// to a bool variable in which to store the value
+// of the environment variable.
+func BoolVar(p *bool, name string, value bool) {
+ *p = value
+ funcs = append(funcs, func() bool {
+ if s := os.Getenv(name); s != "" {
+ v, err := strconv.ParseBool(s)
+ if err != nil {
+ log.Println(name, err)
+ return false
+ }
+ *p = v
+ }
+ return true
+ })
+}
+
+// Duration returns a new time.Duration pointer.
+// When Parse is called,
+// env var name will be parsed
+// and the resulting value
+// will be assigned to the returned location.
+func Duration(name string, value time.Duration) *time.Duration {
+ p := new(time.Duration)
+ DurationVar(p, name, value)
+ return p
+}
+
+// DurationVar defines a time.Duration var with
+// the specified name and default value. The
+// argument p points to a time.Duration variable
+// in which to store the value of the environment
+// variable.
+func DurationVar(p *time.Duration, name string, value time.Duration) {
+ *p = value
+ funcs = append(funcs, func() bool {
+ if s := os.Getenv(name); s != "" {
+ v, err := time.ParseDuration(s)
+ if err != nil {
+ log.Println(name, err)
+ return false
+ }
+ *p = v
+ }
+ return true
+ })
+}
+
+// URL returns a new url.URL pointer.
+// When Parse is called,
+// env var name will be parsed
+// and the resulting value
+// will be assigned to the returned location.
+// URL panics if there is an error parsing
+// the given default value.
+func URL(name string, value string) *url.URL {
+ p := new(url.URL)
+ URLVar(p, name, value)
+ return p
+}
+
+// URLVar defines a url.URL variable with
+// the specified name ande default value.
+// The argument p points to a url.URL variable
+// in which to store the value of the environment
+// variable.
+func URLVar(p *url.URL, name string, value string) {
+ v, err := url.Parse(value)
+ if err != nil {
+ panic(err)
+ }
+ *p = *v
+ funcs = append(funcs, func() bool {
+ if s := os.Getenv(name); s != "" {
+ v, err := url.Parse(s)
+ if err != nil {
+ log.Println(name, err)
+ return false
+ }
+ *p = *v
+ }
+ return true
+ })
+}
+
+// String returns a new string pointer.
+// When Parse is called,
+// env var name will be assigned
+// to the returned location.
+func String(name string, value string) *string {
+ p := new(string)
+ StringVar(p, name, value)
+ return p
+}
+
+// StringVar defines a string with the
+// specified name and default value. The
+// argument p points to a string variable in
+// which to store the value of the environment
+// var.
+func StringVar(p *string, name string, value string) {
+ *p = value
+ funcs = append(funcs, func() bool {
+ if s := os.Getenv(name); s != "" {
+ *p = s
+ }
+ return true
+ })
+}
+
+// StringSlice returns a pointer to a slice
+// of strings. It expects env var name to
+// be a list of items delimited by commas.
+// If env var name is missing, StringSlice
+// returns a pointer to a slice of the value
+// strings.
+func StringSlice(name string, value ...string) *[]string {
+ p := new([]string)
+ StringSliceVar(p, name, value...)
+ return p
+}
+
+// StringSliceVar defines a new string slice
+// with the specified name. The argument p
+// points to a string slice variable in which
+// to store the value of the environment var.
+func StringSliceVar(p *[]string, name string, value ...string) {
+ *p = value
+ funcs = append(funcs, func() bool {
+ if s := os.Getenv(name); s != "" {
+ a := strings.Split(s, ",")
+ *p = a
+ }
+ return true
+ })
+}
+
+// Parse parses known env vars
+// and assigns the values to the variables
+// that were previously registered.
+// If any values cannot be parsed,
+// Parse prints an error message for each one
+// and exits the process with status 1.
+func Parse() {
+ ok := true
+ for _, f := range funcs {
+ ok = f() && ok
+ }
+ if !ok {
+ os.Exit(1)
+ }
+}
--- /dev/null
+package env
+
+import (
+ "net/url"
+ "os"
+ "reflect"
+ "testing"
+ "time"
+)
+
+func TestInt(t *testing.T) {
+ result := Int("nonexistent", 15)
+ Parse()
+
+ if *result != 15 {
+ t.Fatalf("expected result=15, got result=%d", *result)
+ }
+
+ err := os.Setenv("int-key", "25")
+ if err != nil {
+ t.Fatal("unexpected error", err)
+ }
+
+ result = Int("int-key", 15)
+ Parse()
+
+ if *result != 25 {
+ t.Fatalf("expected result=25, got result=%d", *result)
+ }
+}
+
+func TestIntVar(t *testing.T) {
+ var result int
+ IntVar(&result, "nonexistent", 15)
+ Parse()
+
+ if result != 15 {
+ t.Fatalf("expected result=15, got result=%d", result)
+ }
+
+ err := os.Setenv("int-key", "25")
+ if err != nil {
+ t.Fatal("unexpected error", err)
+ }
+
+ IntVar(&result, "int-key", 15)
+ Parse()
+
+ if result != 25 {
+ t.Fatalf("expected result=25, got result=%d", result)
+ }
+}
+
+func TestBool(t *testing.T) {
+ result := Bool("nonexistent", true)
+ Parse()
+
+ if *result != true {
+ t.Fatalf("expected result=true, got result=%t", *result)
+ }
+
+ err := os.Setenv("bool-key", "true")
+ if err != nil {
+ t.Fatal("unexpected error", err)
+ }
+
+ result = Bool("bool-key", false)
+ Parse()
+
+ if *result != true {
+ t.Fatalf("expected result=true, got result=%t", *result)
+ }
+}
+
+func TestBoolVar(t *testing.T) {
+ var result bool
+ BoolVar(&result, "nonexistent", true)
+ Parse()
+
+ if result != true {
+ t.Fatalf("expected result=true, got result=%t", result)
+ }
+
+ err := os.Setenv("bool-key", "true")
+ if err != nil {
+ t.Fatal("unexpected error", err)
+ }
+
+ BoolVar(&result, "bool-key", false)
+ Parse()
+
+ if result != true {
+ t.Fatalf("expected result=true, got result=%t", true)
+ }
+}
+
+func TestDuration(t *testing.T) {
+ result := Duration("nonexistent", 15*time.Second)
+ Parse()
+
+ if *result != 15*time.Second {
+ t.Fatalf("expected result=15s, got result=%v", *result)
+ }
+
+ err := os.Setenv("duration-key", "25s")
+ if err != nil {
+ t.Fatal("unexpected error", err)
+ }
+
+ result = Duration("duration-key", 15*time.Second)
+ Parse()
+
+ if *result != 25*time.Second {
+ t.Fatalf("expected result=25s, got result=%v", *result)
+ }
+}
+
+func TestDurationVar(t *testing.T) {
+ var result time.Duration
+ DurationVar(&result, "nonexistent", 15*time.Second)
+ Parse()
+
+ if result != 15*time.Second {
+ t.Fatalf("expected result=15s, got result=%v", result)
+ }
+
+ err := os.Setenv("duration-key", "25s")
+ if err != nil {
+ t.Fatal("unexpected error", err)
+ }
+
+ DurationVar(&result, "duration-key", 15*time.Second)
+ Parse()
+
+ if result != 25*time.Second {
+ t.Fatalf("expected result=25s, got result=%v", result)
+ }
+}
+
+func TestURL(t *testing.T) {
+ example := "http://example.com"
+ newExample := "http://something-new.com"
+ result := URL("nonexistent", example)
+ Parse()
+
+ if result.String() != example {
+ t.Fatalf("expected result=%s, got result=%v", example, result)
+ }
+
+ err := os.Setenv("url-key", newExample)
+ if err != nil {
+ t.Fatal("unexpected error", err)
+ }
+
+ result = URL("url-key", example)
+ Parse()
+
+ if result.String() != newExample {
+ t.Fatalf("expected result=%v, got result=%v", newExample, result)
+ }
+}
+
+func TestURLVar(t *testing.T) {
+ example := "http://example.com"
+ newExample := "http://something-new.com"
+ var result url.URL
+ URLVar(&result, "nonexistent", example)
+ Parse()
+
+ if result.String() != example {
+ t.Fatalf("expected result=%s, got result=%v", example, result)
+ }
+
+ err := os.Setenv("url-key", newExample)
+ if err != nil {
+ t.Fatal("unexpected error", err)
+ }
+
+ URLVar(&result, "url-key", example)
+ Parse()
+
+ if result.String() != newExample {
+ t.Fatalf("expected result=%v, got result=%v", newExample, result)
+ }
+}
+
+func TestString(t *testing.T) {
+ result := String("nonexistent", "default")
+ Parse()
+
+ if *result != "default" {
+ t.Fatalf("expected result=default, got result=%s", *result)
+ }
+
+ err := os.Setenv("string-key", "something-new")
+ if err != nil {
+ t.Fatal("unexpected error", err)
+ }
+
+ result = String("string-key", "default")
+ Parse()
+
+ if *result != "something-new" {
+ t.Fatalf("expected result=something-new, got result=%s", *result)
+ }
+}
+
+func TestStringVar(t *testing.T) {
+ var result string
+ StringVar(&result, "nonexistent", "default")
+ Parse()
+
+ if result != "default" {
+ t.Fatalf("expected result=default, got result=%s", result)
+ }
+
+ err := os.Setenv("string-key", "something-new")
+ if err != nil {
+ t.Fatal("unexpected error", err)
+ }
+
+ StringVar(&result, "string-key", "default")
+ Parse()
+
+ if result != "something-new" {
+ t.Fatalf("expected result=something-new, got result=%s", result)
+ }
+}
+
+func TestStringSlice(t *testing.T) {
+ result := StringSlice("empty", "hi")
+ Parse()
+
+ exp := []string{"hi"}
+ if !reflect.DeepEqual(exp, *result) {
+ t.Fatalf("expected %v, got %v", exp, *result)
+ }
+
+ err := os.Setenv("string-slice-key", "hello,world")
+ if err != nil {
+ t.Fatal("unexpected error", err)
+ }
+
+ result = StringSlice("string-slice-key", "hi")
+ Parse()
+
+ exp = []string{"hello", "world"}
+ if !reflect.DeepEqual(exp, *result) {
+ t.Fatalf("expected %v, got %v", exp, *result)
+ }
+}
+
+func TestStringSliceVar(t *testing.T) {
+ var result []string
+ StringSliceVar(&result, "empty", "hi")
+ Parse()
+
+ exp := []string{"hi"}
+ if !reflect.DeepEqual(exp, result) {
+ t.Fatalf("expected %v, got %v", exp, result)
+ }
+
+ err := os.Setenv("string-slice-key", "hello,world")
+ if err != nil {
+ t.Fatal("unexpected error", err)
+ }
+
+ StringSliceVar(&result, "string-slice-key", "hi", "there")
+ Parse()
+
+ exp = []string{"hello", "world"}
+ if !reflect.DeepEqual(exp, result) {
+ t.Fatalf("expected %v, got %v", exp, result)
+ }
+}
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