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-rw-r--r--utils/ioutil/common.go18
-rw-r--r--utils/ioutil/common_test.go23
2 files changed, 27 insertions, 14 deletions
diff --git a/utils/ioutil/common.go b/utils/ioutil/common.go
index a847abd..73cc9c3 100644
--- a/utils/ioutil/common.go
+++ b/utils/ioutil/common.go
@@ -1,3 +1,4 @@
+// Package ioutil implements some I/O utility functions.
package ioutil
import (
@@ -63,20 +64,9 @@ func WriteNopCloser(w io.Writer) io.WriteCloser {
return writeNopCloser{w}
}
-// CheckClose is used with defer to close the given io.Closer and check its
-// returned error value. If Close returns an error and the given *error
-// is not nil, *error is set to the error returned by Close.
-//
-// CheckClose is typically used with named return values like so:
-//
-// func do(obj *Object) (err error) {
-// w, err := obj.Writer()
-// if err != nil {
-// return nil
-// }
-// defer CheckClose(w, &err)
-// // work with w
-// }
+// CheckClose calls Close on the given io.Closer. If the given *error points to
+// nil, it will be assigned the error returned by Close. Otherwise, any error
+// returned by Close will be ignored. CheckClose is usually called with defer.
func CheckClose(c io.Closer, err *error) {
if cerr := c.Close(); cerr != nil && *err == nil {
*err = cerr
diff --git a/utils/ioutil/common_test.go b/utils/ioutil/common_test.go
index f5017f7..2d6ef80 100644
--- a/utils/ioutil/common_test.go
+++ b/utils/ioutil/common_test.go
@@ -3,6 +3,7 @@ package ioutil
import (
"bytes"
"io/ioutil"
+ "strings"
"testing"
. "gopkg.in/check.v1"
@@ -53,3 +54,25 @@ func (s *CommonSuite) TestNewReadCloser(c *C) {
c.Assert(r.Close(), IsNil)
c.Assert(closer.called, Equals, 1)
}
+
+func ExampleCheckClose() {
+ // CheckClose is commonly used with named return values
+ f := func() (err error) {
+ // Get a io.ReadCloser
+ r := ioutil.NopCloser(strings.NewReader("foo"))
+
+ // defer CheckClose call with an io.Closer and pointer to error
+ defer CheckClose(r, &err)
+
+ // ... work with r ...
+
+ // if err is not nil, CheckClose will assign any close errors to it
+ return err
+
+ }
+
+ err := f()
+ if err != nil {
+ panic(err)
+ }
+}