reflect: update CanAddr, CanSet documentation
CanAddr was wrong, out of date; CanSet was incomplete.
R=r
CC=golang-dev
https://golang.org/cl/4442066
diff --git a/src/pkg/reflect/value.go b/src/pkg/reflect/value.go
index 44aaebd..3e1ff1e 100644
--- a/src/pkg/reflect/value.go
+++ b/src/pkg/reflect/value.go
@@ -395,8 +395,7 @@
// CanAddr returns true if the value's address can be obtained with Addr.
// Such values are called addressable. A value is addressable if it is
// an element of a slice, an element of an addressable array,
-// a field of an addressable struct, the result of dereferencing a pointer,
-// or the result of a call to NewValue, MakeChan, MakeMap, or Zero.
+// a field of an addressable struct, or the result of dereferencing a pointer.
// If CanAddr returns false, calling Addr will panic.
func (v Value) CanAddr() bool {
iv := v.internal()
@@ -404,8 +403,8 @@
}
// CanSet returns true if the value of v can be changed.
-// Values obtained by the use of unexported struct fields
-// can be read but not set.
+// A Value can be changed only if it is addressable and was not
+// obtained by the use of unexported struct fields.
// If CanSet returns false, calling Set or any type-specific
// setter (e.g., SetBool, SetInt64) will panic.
func (v Value) CanSet() bool {
