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encoding/binary: hide TotalSize

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The function has a bizarre signature: it was the only public function there
that exposed the reflect package. Also, its definition is peculiar and hard to
explain. It doesn't merit being exported.

This is an API change but really, it should never have been exported and
it's certain very few programs will depend on it: it's too weird.

Fixes #2846.

R=golang-dev, gri, bradfitz
CC=golang-dev
https://golang.org/cl/5639054
This commit is contained in:
Rob Pike 2012-02-08 14:09:20 +11:00
parent f23a6dba5e
commit 52ebadd356
4 changed files with 118 additions and 92 deletions
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99
doc/go1.html
View File

@ -929,6 +929,61 @@ to be implemented in the future.
No changes will be needed.
</p>
<h3 id="encoding_binary">The encoding/binary package</h3>
<p>
In Go 1, the <code>binary.TotalSize</code></a> function is no longer exported.
</p>
<p>
<em>Updating</em>:
Code that depends on the function will need to be updated.
</p>
<h3 id="encoding_xml">The encoding/xml package</h3>
<p>
In Go 1, the <a href="/pkg/encoding/xml/"><code>xml</code></a> package
has been brought closer in design to the other marshaling packages such
as <a href="/pkg/encoding/gob/"><code>encoding/gob</code></a>.
</p>
<p>
The old <code>Parser</code> type is renamed
<a href="/pkg/encoding/xml/#Decoder"><code>Decoder</code></a> and has a new
<a href="/pkg/encoding/xml/#Decoder.Decode"><code>Decode</code></a> method. An
<a href="/pkg/encoding/xml/#Encoder"><code>Encoder</code></a> type was also
introduced.
</p>
<p>
The functions <a href="/pkg/encoding/xml/#Marshal"><code>Marshal</code></a>
and <a href="/pkg/encoding/xml/#Unmarshal"><code>Unmarshal</code></a>
work with <code>[]byte</code> values now. To work with streams,
use the new <a href="/pkg/encoding/xml/#Encoder"><code>Encoder</code></a>
and <a href="/pkg/encoding/xml/#Decoder"><code>Decoder</code></a> types.
</p>
<p>
When marshaling or unmarshaling values, the format of supported flags in
field tags has changed to be closer to the
<a href="/pkg/encoding/json"><code>json</code></a> package
(<code>`xml:"name,flag"`</code>). The matching done between field tags, field
names, and the XML attribute and element names is now case-sensitive.
The <code>XMLName</code> field tag, if present, must also match the name
of the XML element being marshaled.
</p>
<p>
<em>Updating</em>:
Running <code>go fix</code> will update most uses of the package except for some calls to
<code>Unmarshal</code>. Special care must be taken with field tags,
since the fix tool will not update them and if not fixed by hand they will
misbehave silently in some cases. For example, the old
<code>"attr"</code> is now written <code>",attr"</code> while plain
<code>"attr"</code> remains valid but with a different meaning.
</p>
<h3 id="expvar">The expvar package</h3>
<p>
@ -1575,50 +1630,6 @@ Code that uses the old fields will fail to compile and must be updated by hand.
The semantic changes make it difficult for the fix tool to update automatically.
</p>
<h3 id="xml">The xml package</h3>
<p>
In Go 1, the <a href="/pkg/encoding/xml/"><code>xml</code></a> package
has been brought closer in design to the other marshaling packages such
as <a href="/pkg/encoding/gob/"><code>encoding/gob</code></a>.
</p>
<p>
The old <code>Parser</code> type is renamed
<a href="/pkg/encoding/xml/#Decoder"><code>Decoder</code></a> and has a new
<a href="/pkg/encoding/xml/#Decoder.Decode"><code>Decode</code></a> method. An
<a href="/pkg/encoding/xml/#Encoder"><code>Encoder</code></a> type was also
introduced.
</p>
<p>
The functions <a href="/pkg/encoding/xml/#Marshal"><code>Marshal</code></a>
and <a href="/pkg/encoding/xml/#Unmarshal"><code>Unmarshal</code></a>
work with <code>[]byte</code> values now. To work with streams,
use the new <a href="/pkg/encoding/xml/#Encoder"><code>Encoder</code></a>
and <a href="/pkg/encoding/xml/#Decoder"><code>Decoder</code></a> types.
</p>
<p>
When marshaling or unmarshaling values, the format of supported flags in
field tags has changed to be closer to the
<a href="/pkg/encoding/json"><code>json</code></a> package
(<code>`xml:"name,flag"`</code>). The matching done between field tags, field
names, and the XML attribute and element names is now case-sensitive.
The <code>XMLName</code> field tag, if present, must also match the name
of the XML element being marshaled.
</p>
<p>
<em>Updating</em>:
Running <code>go fix</code> will update most uses of the package except for some calls to
<code>Unmarshal</code>. Special care must be taken with field tags,
since the fix tool will not update them and if not fixed by hand they will
misbehave silently in some cases. For example, the old
<code>"attr"</code> is now written <code>",attr"</code> while plain
<code>"attr"</code> remains valid but with a different meaning.
</p>
<h2 id="go_command">The go command</h2>
<h2 id="releases">Packaged releases</h2>

99
doc/go1.tmpl
View File

@ -833,6 +833,61 @@ to be implemented in the future.
No changes will be needed.
</p>
<h3 id="encoding_binary">The encoding/binary package</h3>
<p>
In Go 1, the <code>binary.TotalSize</code></a> function is no longer exported.
</p>
<p>
<em>Updating</em>:
Code that depends on the function will need to be updated.
</p>
<h3 id="encoding_xml">The encoding/xml package</h3>
<p>
In Go 1, the <a href="/pkg/encoding/xml/"><code>xml</code></a> package
has been brought closer in design to the other marshaling packages such
as <a href="/pkg/encoding/gob/"><code>encoding/gob</code></a>.
</p>
<p>
The old <code>Parser</code> type is renamed
<a href="/pkg/encoding/xml/#Decoder"><code>Decoder</code></a> and has a new
<a href="/pkg/encoding/xml/#Decoder.Decode"><code>Decode</code></a> method. An
<a href="/pkg/encoding/xml/#Encoder"><code>Encoder</code></a> type was also
introduced.
</p>
<p>
The functions <a href="/pkg/encoding/xml/#Marshal"><code>Marshal</code></a>
and <a href="/pkg/encoding/xml/#Unmarshal"><code>Unmarshal</code></a>
work with <code>[]byte</code> values now. To work with streams,
use the new <a href="/pkg/encoding/xml/#Encoder"><code>Encoder</code></a>
and <a href="/pkg/encoding/xml/#Decoder"><code>Decoder</code></a> types.
</p>
<p>
When marshaling or unmarshaling values, the format of supported flags in
field tags has changed to be closer to the
<a href="/pkg/encoding/json"><code>json</code></a> package
(<code>`xml:"name,flag"`</code>). The matching done between field tags, field
names, and the XML attribute and element names is now case-sensitive.
The <code>XMLName</code> field tag, if present, must also match the name
of the XML element being marshaled.
</p>
<p>
<em>Updating</em>:
Running <code>go fix</code> will update most uses of the package except for some calls to
<code>Unmarshal</code>. Special care must be taken with field tags,
since the fix tool will not update them and if not fixed by hand they will
misbehave silently in some cases. For example, the old
<code>"attr"</code> is now written <code>",attr"</code> while plain
<code>"attr"</code> remains valid but with a different meaning.
</p>
<h3 id="expvar">The expvar package</h3>
<p>
@ -1465,50 +1520,6 @@ Code that uses the old fields will fail to compile and must be updated by hand.
The semantic changes make it difficult for the fix tool to update automatically.
</p>
<h3 id="xml">The xml package</h3>
<p>
In Go 1, the <a href="/pkg/encoding/xml/"><code>xml</code></a> package
has been brought closer in design to the other marshaling packages such
as <a href="/pkg/encoding/gob/"><code>encoding/gob</code></a>.
</p>
<p>
The old <code>Parser</code> type is renamed
<a href="/pkg/encoding/xml/#Decoder"><code>Decoder</code></a> and has a new
<a href="/pkg/encoding/xml/#Decoder.Decode"><code>Decode</code></a> method. An
<a href="/pkg/encoding/xml/#Encoder"><code>Encoder</code></a> type was also
introduced.
</p>
<p>
The functions <a href="/pkg/encoding/xml/#Marshal"><code>Marshal</code></a>
and <a href="/pkg/encoding/xml/#Unmarshal"><code>Unmarshal</code></a>
work with <code>[]byte</code> values now. To work with streams,
use the new <a href="/pkg/encoding/xml/#Encoder"><code>Encoder</code></a>
and <a href="/pkg/encoding/xml/#Decoder"><code>Decoder</code></a> types.
</p>
<p>
When marshaling or unmarshaling values, the format of supported flags in
field tags has changed to be closer to the
<a href="/pkg/encoding/json"><code>json</code></a> package
(<code>`xml:"name,flag"`</code>). The matching done between field tags, field
names, and the XML attribute and element names is now case-sensitive.
The <code>XMLName</code> field tag, if present, must also match the name
of the XML element being marshaled.
</p>
<p>
<em>Updating</em>:
Running <code>go fix</code> will update most uses of the package except for some calls to
<code>Unmarshal</code>. Special care must be taken with field tags,
since the fix tool will not update them and if not fixed by hand they will
misbehave silently in some cases. For example, the old
<code>"attr"</code> is now written <code>",attr"</code> while plain
<code>"attr"</code> remains valid but with a different meaning.
</p>
<h2 id="go_command">The go command</h2>
<h2 id="releases">Packaged releases</h2>

10
src/pkg/encoding/binary/binary.go
View File

@ -163,7 +163,7 @@ func Read(r io.Reader, order ByteOrder, data interface{}) error {
default:
return errors.New("binary.Read: invalid type " + d.Type().String())
}
size := TotalSize(v)
size := dataSize(v)
if size < 0 {
return errors.New("binary.Read: invalid type " + v.Type().String())
}
@ -242,7 +242,7 @@ func Write(w io.Writer, order ByteOrder, data interface{}) error {
return err
}
v := reflect.Indirect(reflect.ValueOf(data))
size := TotalSize(v)
size := dataSize(v)
if size < 0 {
return errors.New("binary.Write: invalid type " + v.Type().String())
}
@ -253,7 +253,11 @@ func Write(w io.Writer, order ByteOrder, data interface{}) error {
return err
}
func TotalSize(v reflect.Value) int {
// dataSize returns the number of bytes the actual data represented by v occupies in memory.
// For compound structures, it sums the sizes of the elements. Thus, for instance, for a slice
// it returns the length of the slice times the element size and does not count the memory
// occupied by the header.
func dataSize(v reflect.Value) int {
if v.Kind() == reflect.Slice {
elem := sizeof(v.Type().Elem())
if elem < 0 {

2
src/pkg/encoding/binary/binary_test.go
View File

@ -187,7 +187,7 @@ func BenchmarkReadStruct(b *testing.B) {
bsr := &byteSliceReader{}
var buf bytes.Buffer
Write(&buf, BigEndian, &s)
n := TotalSize(reflect.ValueOf(s))
n := dataSize(reflect.ValueOf(s))
b.SetBytes(int64(n))
t := s
b.ResetTimer()