os: Add example for Expand function.

Change-Id: I581492c29158e57ca2f98b75f47870791965a7ff
Reviewed-on: https://go-review.googlesource.com/81155
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/os/example_test.go b/src/os/example_test.go
index 5749194871b795f6e49cb8b64d799abbc1e2e1b2..e21415a3fda9ea50afc4c77a163132b8e247a23d 100644 (file)
--- a/src/os/example_test.go
+++ b/src/os/example_test.go
@@ -82,6 +82,24 @@ func init() {
        os.Unsetenv("GOPATH")
 }
 
+func ExampleExpand() {
+       mapper := func(placeholderName string) string {
+               switch placeholderName {
+               case "DAY_PART":
+                       return "morning"
+               case "USER":
+                       return "Gopher"
+               }
+
+               return ""
+       }
+
+       fmt.Println(os.Expand("Good ${DAY_PART}, $USER!", mapper))
+
+       // Output:
+       // Good morning, Gopher!
+}
+
 func ExampleExpandEnv() {
        fmt.Println(os.ExpandEnv("$USER lives in ${HOME}."))