document io

R=rsc
DELTA=44  (30 added, 4 deleted, 10 changed)
OCL=25819
CL=25835

1 files changed, 21 insertions, 5 deletions

diff --git a/src/lib/io/io.go b/src/lib/io/io.go
index e5f02eb70..37acab4c7 100644
--- a/src/lib/io/io.go
+++ b/src/lib/io/io.go
@@ -2,6 +2,11 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// This package provides basic interfaces to I/O primitives.
+// Its primary job is to wrap existing implementations of such primitives,
+// such as those in package os, into shared public interfaces that
+// abstract the functionality.
+// It also provides buffering primitives and some other basic operations.
 package io
 
 import (
@@ -9,35 +14,43 @@ import (
 	"syscall";
 )
 
+// ErrEOF is the error returned by Readn and Copyn when they encounter EOF.
 var ErrEOF = os.NewError("EOF")
 
+// Read is the interface that wraps the basic Read method.
 type Read interface {
 	Read(p []byte) (n int, err *os.Error);
 }
 
+// Write is the interface that wraps the basic Write method.
 type Write interface {
 	Write(p []byte) (n int, err *os.Error);
 }
 
+// Close is the interface that wraps the basic Close method.
 type Close interface {
 	Close() *os.Error;
 }
 
+// ReadWrite is the interface that groups the basic Read and Write methods.
 type ReadWrite interface {
 	Read;
 	Write;
 }
 
+// ReadClose is the interface that groups the basic Read and Close methods.
 type ReadClose interface {
 	Read;
 	Close;
 }
 
+// WriteClose is the interface that groups the basic Write and Close methods.
 type WriteClose interface {
 	Write;
 	Close;
 }
 
+// ReadWriteClose is the interface that groups the basic Read, Write and Close methods.
 type ReadWriteClose interface {
 	Read;
 	Write;
@@ -53,11 +66,12 @@ func StringBytes(s string) []byte {
 	return b;
 }
 
+// WriteString writes the contents of the string s to w, which accepts an array of bytes.
 func WriteString(w Write, s string) (n int, err *os.Error) {
 	return w.Write(StringBytes(s))
 }
 
-// Read until buffer is full, EOF, or error
+// Readn reads r until the buffer buf is full, or until EOF or error.
 func Readn(r Read, buf []byte) (n int, err *os.Error) {
 	n = 0;
 	for n < len(buf) {
@@ -86,6 +100,8 @@ func (fr *fullRead) Read(p []byte) (n int, err *os.Error) {
 	return n, err
 }
 
+// MakeFullReader takes r, an implementation of Read, and returns an object
+// that still implements Read but always calls Readn underneath.
 func MakeFullReader(r Read) Read {
 	if fr, ok := r.(*fullRead); ok {
 		// already a fullRead
@@ -94,8 +110,8 @@ func MakeFullReader(r Read) Read {
 	return &fullRead{r}
 }
 
-// Copies n bytes (or until EOF is reached) from src to dst.
-// Returns the number of bytes copied and the error, if any.
+// Copy n copies n bytes (or until EOF is reached) from src to dst.
+// It returns the number of bytes copied and the error, if any.
 func Copyn(src Read, dst Write, n int64) (written int64, err *os.Error) {
 	buf := make([]byte, 32*1024);
 	for written < n {
@@ -130,8 +146,8 @@ func Copyn(src Read, dst Write, n int64) (written int64, err *os.Error) {
 	return written, err
 }
 
-// Copies from src to dst until EOF is reached.
-// Returns the number of bytes copied and the error, if any.
+// Copy copies from src to dst until EOF is reached.
+// It returns the number of bytes copied and the error, if any.
 func Copy(src Read, dst Write) (written int64, err *os.Error) {
 	buf := make([]byte, 32*1024);
 	for {