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doc: add type aliases to go1.9.html

Updates #20587

Change-Id: I5df603505ae1d4b65687bec1e973a4ab318b34f1
Reviewed-on: https://go-review.googlesource.com/45014
Reviewed-by: Robert Griesemer <gri@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
This commit is contained in:
Brad Fitzpatrick 2017-06-06 22:03:45 +00:00
parent 4e7067cde4
commit 90b39f33c4

View File

@ -23,12 +23,18 @@ ul li { margin: 0.5em 0; }
</strong></p>
<p>
The latest Go release, version 1.9, arrives six months after <a href="go1.8">Go 1.8</a>
and is the tenth release in the <a href="https://golang.org/doc/devel/release.html">Go 1.x series</a>.
Most of its changes are in the implementation of the toolchain, runtime, and libraries.
There are no changes to the language specification.
As always, the release maintains the Go 1 <a href="/doc/go1compat.html">promise of compatibility</a>.
We expect almost all Go programs to continue to compile and run as before.
The latest Go release, version 1.9, arrives six months
after <a href="go1.8">Go 1.8</a> and is the tenth release in
the <a href="https://golang.org/doc/devel/release.html">Go 1.x
series</a>.
There is one <a href="#language">change to the language</a>, adding
support for type aliases.
Most of the changes are in the implementation of the toolchain,
runtime, and libraries.
As always, the release maintains the Go 1
<a href="/doc/go1compat.html">promise of compatibility</a>.
We expect almost all Go programs to continue to compile and run as
before.
</p>
<p>
@ -39,6 +45,29 @@ ul li { margin: 0.5em 0; }
and includes a new <a href="#math-bits">bit manipulation package</a>.
</p>
<h2 id="language">Changes to the language</h2>
<p>
There is one change to the language.
Go now supports type aliases to support gradual code repair while
moving a type between packages.
The <a href="https://golang.org/design/18130-type-alias">type alias
design document</a>
and <a href="https://talks.golang.org/2016/refactor.article">an
article on refactoring</a> cover the problem in detail.
In short, a type alias declaration has the form:
</p>
<pre>
type T1 = T2
</pre>
<p>
This declaration introduces an alias name <code>T1</code>—an
alternate spelling—for the type denoted by <code>T2</code>; that is,
both <code>T1</code> and <code>T2</code> denote the same type.
</p>
<h2 id="ports">Ports</h2>
<p>
@ -147,7 +176,7 @@ ul li { margin: 0.5em 0; }
The
new <a href="/pkg/testing/#T.Helper"><code>(*T).Helper</code></a>
an <a href="/pkg/testing/#B.Helper"><code>(*B).Helper</code></a>
methods marks the calling function as a test helper function. When
methods mark the calling function as a test helper function. When
printing file and line information, that function will be skipped.
This permits writing test helper functions while still having useful
line numbers for users.