tutorial: modernize the definition and use of Open.

R=golang-dev, iant
CC=golang-dev
http://codereview.appspot.com/4446053

4 files changed, 21 insertions, 4 deletions

diff --git a/doc/progs/cat.go b/doc/progs/cat.go
index 697e5f786..9f0b8d4a3 100644
--- a/doc/progs/cat.go
+++ b/doc/progs/cat.go
@@ -24,6 +24,7 @@ func cat(f *file.File) {
 		case nr > 0:
 			if nw, ew := file.Stdout.Write(buf[0:nr]); nw != nr {
 				fmt.Fprintf(os.Stderr, "cat: error writing from %s: %s\n", f.String(), ew.String())
+				os.Exit(1)
 			}
 		}
 	}
@@ -35,7 +36,7 @@ func main() {
 		cat(file.Stdin)
 	}
 	for i := 0; i < flag.NArg(); i++ {
-		f, err := file.Open(flag.Arg(i), 0, 0)
+		f, err := file.Open(flag.Arg(i))
 		if f == nil {
 			fmt.Fprintf(os.Stderr, "cat: can't open %s: error %s\n", flag.Arg(i), err)
 			os.Exit(1)
diff --git a/doc/progs/cat_rot13.go b/doc/progs/cat_rot13.go
index 03fc02259..0eefe7cfc 100644
--- a/doc/progs/cat_rot13.go
+++ b/doc/progs/cat_rot13.go
@@ -67,6 +67,7 @@ func cat(r reader) {
 			nw, ew := file.Stdout.Write(buf[0:nr])
 			if nw != nr {
 				fmt.Fprintf(os.Stderr, "cat: error writing from %s: %s\n", r.String(), ew.String())
+				os.Exit(1)
 			}
 		}
 	}
@@ -78,7 +79,7 @@ func main() {
 		cat(file.Stdin)
 	}
 	for i := 0; i < flag.NArg(); i++ {
-		f, err := file.Open(flag.Arg(i), 0, 0)
+		f, err := file.Open(flag.Arg(i))
 		if f == nil {
 			fmt.Fprintf(os.Stderr, "cat: can't open %s: error %s\n", flag.Arg(i), err)
 			os.Exit(1)
diff --git a/doc/progs/file.go b/doc/progs/file.go
index df3a3cf71..2875ce73a 100644
--- a/doc/progs/file.go
+++ b/doc/progs/file.go
@@ -27,7 +27,7 @@ var (
 	Stderr = newFile(syscall.Stderr, "/dev/stderr")
 )
 
-func Open(name string, mode int, perm uint32) (file *File, err os.Error) {
+func OpenFile(name string, mode int, perm uint32) (file *File, err os.Error) {
 	r, e := syscall.Open(name, mode, perm)
 	if e != 0 {
 		err = os.Errno(e)
@@ -35,6 +35,21 @@ func Open(name string, mode int, perm uint32) (file *File, err os.Error) {
 	return newFile(r, name), err
 }
 
+const (
+	O_RDONLY = syscall.O_RDONLY
+	O_RDWR   = syscall.O_RDWR
+	O_CREATE = syscall.O_CREAT
+	O_TRUNC  = syscall.O_TRUNC
+)
+
+func Open(name string) (file *File, err os.Error) {
+	return OpenFile(name, O_RDONLY, 0)
+}
+
+func Create(name string) (file *File, err os.Error) {
+	return OpenFile(name, O_RDWR|O_CREATE|O_TRUNC, 0666)
+}
+
 func (file *File) Close() os.Error {
 	if file == nil {
 		return os.EINVAL
diff --git a/doc/progs/helloworld3.go b/doc/progs/helloworld3.go
index adbcea324..5bb0be218 100644
--- a/doc/progs/helloworld3.go
+++ b/doc/progs/helloworld3.go
@@ -13,7 +13,7 @@ import (
 func main() {
 	hello := []byte("hello, world\n")
 	file.Stdout.Write(hello)
-	f, err := file.Open("/does/not/exist",  0,  0)
+	f, err := file.Open("/does/not/exist")
 	if f == nil {
 		fmt.Printf("can't open file; err=%s\n",  err.String())
 		os.Exit(1)