mirror of
https://github.com/golang/go
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1568 lines
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1568 lines
50 KiB
Cheetah
<!--{
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"Title": "Go 1 Release Notes"
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}-->
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{{donotedit}}
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<h2 id="introduction">Introduction to Go 1</h2>
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<p>
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For a full explanation of the motivation and design of Go 1, see XXX.
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Here follows a summary.
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</p>
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<p>
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Go 1 is intended to be a stable language and core library set that
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will form a reliable foundation for people and organizations that
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want to make a long-term commitment to developing in the Go programming
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language. Go will continue to develop, but in a way that guarantees
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code written to the Go 1 specification will continue to work. For
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instance, Go 1 will be a supported platform on Google App Engine
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for the next few years. Incompatible changes to the environment,
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should they arise, will be done in a distinct version.
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</p>
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<p>
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This document describes the changes in the language and libraries
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in Go 1, relative to the previous release, r60 (at the time of
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writing, tagged as r60.3). It also explains how to update code at
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r60 to compile and run under Go 1. Finally, it outlines the new
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<code>go</code> command for building Go programs and the new binary
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release process being introduced. Most of these topics have more
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thorough presentations elsewhere; such documents are linked below.
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</p>
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<h2 id="language">Changes to the language</h2>
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<h3 id="append">Append</h3>
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<p>
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The <code>append</code> built-in function is variadic, so one can
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append to a byte slice using the <code>...</code> syntax in the
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call.
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</p>
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{{code "progs/go1.go" `/greeting := ..byte/` `/append.*hello/`}}
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<p>
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By analogy with the similar property of <code>copy</code>, Go 1
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permits a string to be appended (byte-wise) directly to a byte
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slice; the conversion is no longer necessary:
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</p>
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{{code "progs/go1.go" `/append.*world/`}}
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<p>
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<em>Updating</em>:
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This is a new feature, so existing code needs no changes.
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</p>
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<h3 id="close">Close</h3>
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<p>
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The <code>close</code> built-in function lets a sender tell a receiver
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that no more data will be transmitted on the channel. In Go 1 the
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type system enforces the directionality when possible: it is illegal
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to call <code>close</code> on a receive-only channel:
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</p>
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<pre>
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var c chan int
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var csend chan<- int = c
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var crecv <-chan int = c
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close(c) // legal
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close(csend) // legal
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close(crecv) // illegal
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</pre>
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<p>
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<em>Updating</em>:
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Existing code that attempts to close a receive-only channel was
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erroneous even before Go 1 and should be fixed. The compiler will
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now reject such code.
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</p>
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<h3 id="literals">Composite literals</h3>
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<p>
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In Go 1, a composite literal of array, slice, or map type can elide the
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type specification for the elements' initializers if they are of pointer type.
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All four of the initializations in this example are legal; the last one was illegal before Go 1.
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</p>
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{{code "progs/go1.go" `/type Date struct/` `/STOP/`}}
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<p>
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<em>Updating</em>:
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This change has no effect on existing code, but the command
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<code>gofmt</code> <code>-s</code> applied to existing source
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will, among other things, elide explicit element types wherever permitted.
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</p>
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<h3 id="init">Goroutines during init</h3>
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<p>
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Go 1 allows goroutines to be created and run during initialization.
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(They used to be created but were not run until after initialization
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completed.) Code that uses goroutines can now be called from
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<code>init</code> routines and global initialization expressions
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without introducing a deadlock.
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</p>
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{{code "progs/go1.go" `/PackageGlobal/` `/^}/`}}
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<p>
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<em>Updating</em>:
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This is a new feature, so existing code needs no changes,
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although it's possible that code that depends on goroutines not starting before <code>main</code> will break.
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There was no such code in the standard repository.
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</p>
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<h3 id="rune">The rune type</h3>
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<p>
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Go 1 introduces a new basic type, <code>rune</code>, to be used to represent
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individual Unicode code points.
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It is an alias for <code>int32</code>, analogous to <code>byte</code>
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as an alias for <code>uint8</code>.
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</p>
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<p>
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Character literals such as <code>'a'</code>, <code>'語'</code>, and <code>'\u0345'</code>
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now have default type <code>rune</code>,
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analogous to <code>1.0</code> having default type <code>float64</code>.
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A variable initialized to a character constant will therefore
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have type <code>rune</code> unless otherwise specified.
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</p>
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<p>
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Libraries have been updated to use <code>rune</code> rather than <code>int</code>
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when appropriate. For instance, the functions <code>unicode.ToLower</code> and
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relatives now take and return a <code>rune</code>.
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</p>
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{{code "progs/go1.go" `/STARTRUNE/` `/ENDRUNE/`}}
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<p>
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<em>Updating</em>:
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Most source code will be unaffected by this because the type inference from
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<code>:=</code> initializers introduces the new type silently, and it propagates
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from there.
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Some code may get type errors that a trivial conversion will resolve.
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</p>
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<h3 id="error">The error type</h3>
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<p>
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Go 1 introduces a new built-in type, <code>error</code>, which has the following definition:
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</p>
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<pre>
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type error interface {
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Error() string
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}
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</pre>
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<p>
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Since the consequences of this type are all in the package library,
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it is discussed <a href="#errors">below</a>.
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</p>
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<h3 id="delete">Deleting from maps</h3>
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<p>
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The original syntax for deleting an element in a map was:
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</p>
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<pre>
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m[k] = ignored, false
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</pre>
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<p>
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In Go 1, that syntax has gone; instead there is a new built-in
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function, <code>delete</code>. The call
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</p>
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{{code "progs/go1.go" `/delete\(m, k\)/`}}
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<p>
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will delete the map entry retrieved by the expression <code>m[k]</code>.
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There is no return value. Deleting a non-existent entry is a no-op.
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</p>
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<p>
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<em>Updating</em>:
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Running <code>go fix</code> will convert expressions of the form <code>m[k] = ignored,
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false</code> into <code>delete(m, k)</code> when it is clear that
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the ignored value can be safely discarded from the program and
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<code>false</code> refers to the predefined boolean constant.
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The fix tool
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will flag other uses of the syntax for inspection by the programmer.
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</p>
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<h3 id="iteration">Iterating in maps</h3>
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<p>
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In Go 1, the order in which elements are visited when iterating
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over a map using a <code>for</code> <code>range</code> statement
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is defined to be unpredictable, even if the same loop is run multiple
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times with the same map.
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Code should not assume that the elements are visited in any particular order.
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</p>
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{{code "progs/go1.go" `/Sunday/` `/^ }/`}}
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<p>
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<em>Updating</em>:
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This is one change where tools cannot help. Most existing code
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will be unaffected, but some programs may break or misbehave; we
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recommend manual checking of all range statements over maps to
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verify they do not depend on iteration order. There were a few such
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examples in the standard repository; they have been fixed.
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Note that it was already incorrect to depend on the iteration order, which
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was unspecified. This change codifies the unpredictability.
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</p>
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<h3 id="multiple_assignment">Multiple assignment</h3>
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<p>
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Go 1 fully specifies the evaluation order in multiple assignment
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statements. In particular, if the left-hand side of the assignment
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statement contains expressions that require evaluation, such as
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function calls or array indexing operations, these will all be done
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using the usual left-to-right rule before any variables are assigned
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their value. Once everything is evaluated, the actual assignments
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proceed in left-to-right order.
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</p>
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<p>
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These examples illustrate the behavior.
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</p>
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{{code "progs/go1.go" `/sa :=/` `/then sc.0. = 2/`}}
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<p>
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<em>Updating</em>:
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This is one change where tools cannot help, but breakage is unlikely.
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No code in the standard repository was broken by this change, and code
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that depended on the previous unspecified behavior was already incorrect.
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</p>
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<h3 id="shadowing">Returns and shadowed variables</h3>
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<p>
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A shadowed variable is one that has the same name as another variable in an inner scope.
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In functions with named return values,
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the Go 1 compilers disallow return statements without arguments if any of the named return values is shadowed at the point of the return statement.
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(It isn't part of the specification, because this is one area we are still exploring;
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the situation is analogous to the compilers rejecting functions that do not end with an explicit return statement.)
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</p>
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<p>
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This function implicitly returns a shadowed return value and will be rejected by the compiler:
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</p>
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<pre>
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func Bug() (i, j, k int) {
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for i = 0; i < 5; i++ {
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for j := 0; j < 5; j++ { // Redeclares j.
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k += i*j
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if k > 100 {
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return // Rejected: j is shadowed here.
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}
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}
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}
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return // OK: j is not shadowed here.
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}
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</pre>
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<p>
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<em>Updating</em>:
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Code that shadows return values in this way will be rejected by the compiler and will need to be fixed by hand.
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The few cases that arose in the standard repository were mostly bugs.
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</p>
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<h3 id="unexported">Copying structs with unexported fields</h3>
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<p>
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Go 1 relaxes the rules about accessing structs with unexported (lower-case) fields,
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permitting a client package to assign (and therefore copy) such a struct.
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Of course, the client package still cannot access such fields individually.
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</p>
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<p>
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As an example, if package <code>p</code> includes the definitions,
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</p>
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<pre>
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type Struct struct {
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Public int
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secret int
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}
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func NewStruct(a int) Struct { // Note: not a pointer.
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return Struct{a, f(a)}
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}
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func (s Struct) String() string {
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return fmt.Sprintf("{%d (secret %d)}", s.Public, s.secret)
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}
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</pre>
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<p>
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a package that imports <code>p</code> can assign and copy values of type
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<code>p.Struct</code> at will.
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Behind the scenes the unexported fields will be assigned and copied just
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as if they were exported,
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but the client code will never be aware of them. The code
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</p>
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<pre>
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import "p"
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myStruct := p.NewStruct(23)
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copyOfMyStruct := myStruct
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fmt.Println(myStruct, copyOfMyStruct)
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</pre>
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<p>
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will show that the secret field of the struct has been copied to the new value.
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</p>
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<p>
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<em>Updating</em>:
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This is a new feature, so existing code needs no changes.
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</p>
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<h3 id="equality">Equality of structs and arrays</h3>
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<p>
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Go 1 defines equality and inequality (<code>==</code> and
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<code>!=</code>) for struct and array values, respectively, provided
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the elements of the data structures can themselves be compared.
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That is, if equality is defined for all the fields of a struct (or
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an array element), then it is defined for the struct (or array).
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</p>
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<p>
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As a result, structs and arrays can now be used as map keys:
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</p>
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{{code "progs/go1.go" `/type Day struct/` `/Printf/`}}
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<p>
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Note that equality is still undefined for slices, for which the
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calculation is in general infeasible. Also note that the ordered
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comparison operators (<code><</code> <code><=</code>
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<code>></code> <code>>=</code>) are still undefined for
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structs and arrays.
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<p>
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<em>Updating</em>:
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This is a new feature, so existing code needs no changes.
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</p>
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<h3 id="funcs">Function and map equality</h3>
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<p>
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Go 1 disallows checking for equality of functions and maps,
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respectively, except to compare them directly to <code>nil</code>.
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</p>
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<p>
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<em>Updating</em>:
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Existing code that depends on function or map equality will be
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rejected by the compiler and will need to be fixed by hand.
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Few programs will be affected, but the fix may require some
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redesign.
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</p>
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<h2 id="packages">The package hierarchy</h2>
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<p>
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This section describes how the packages have been rearranged in Go 1.
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Some have moved, some have been renamed, some have been deleted.
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New packages are described in later sections.
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</p>
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<h3 id="hierarchy">The package hierarchy</h3>
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<p>
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Go 1 has a rearranged package hierarchy that groups related items
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into subdirectories. For instance, <code>utf8</code> and
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<code>utf16</code> now occupy subdirectories of <code>unicode</code>.
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Also, <a href="#subrepo">some packages</a> have moved into
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subrepositories of
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<a href="http://code.google.com/p/go"><code>code.google.com/p/go</code></a>
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while <a href="#deleted">others</a> have been deleted outright.
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</p>
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<table class="codetable" frame="border" summary="Moved packages">
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<colgroup align="left" width="60%"></colgroup>
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<colgroup align="left" width="40%"></colgroup>
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<tr>
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<th align="left">Old path</th>
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<th align="left">New path</th>
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</tr>
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<tr>
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<td colspan="2"><hr></td>
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</tr>
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<tr><td>asn1</td> <td>encoding/asn1</td></tr>
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<tr><td>csv</td> <td>encoding/csv</td></tr>
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<tr><td>gob</td> <td>encoding/gob</td></tr>
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<tr><td>json</td> <td>encoding/json</td></tr>
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<tr><td>xml</td> <td>encoding/xml</td></tr>
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<tr>
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<td colspan="2"><hr></td>
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</tr>
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<tr><td>exp/template/html</td> <td>html/template</td></tr>
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<tr>
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<td colspan="2"><hr></td>
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</tr>
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<tr><td>big</td> <td>math/big</td></tr>
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<tr><td>cmath</td> <td>math/cmplx</td></tr>
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<tr><td>rand</td> <td>math/rand</td></tr>
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<tr>
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<td colspan="2"><hr></td>
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</tr>
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<tr><td>http</td> <td>net/http</td></tr>
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<tr><td>http/cgi</td> <td>net/http/cgi</td></tr>
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<tr><td>http/fcgi</td> <td>net/http/fcgi</td></tr>
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<tr><td>http/httptest</td> <td>net/http/httptest</td></tr>
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<tr><td>http/pprof</td> <td>net/http/pprof</td></tr>
|
|
<tr><td>mail</td> <td>net/mail</td></tr>
|
|
<tr><td>rpc</td> <td>net/rpc</td></tr>
|
|
<tr><td>rpc/jsonrpc</td> <td>net/rpc/jsonrpc</td></tr>
|
|
<tr><td>smtp</td> <td>net/smtp</td></tr>
|
|
<tr><td>url</td> <td>net/url</td></tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>exec</td> <td>os/exec</td></tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>scanner</td> <td>text/scanner</td></tr>
|
|
<tr><td>tabwriter</td> <td>text/tabwriter</td></tr>
|
|
<tr><td>template</td> <td>text/template</td></tr>
|
|
<tr><td>template/parse</td> <td>text/template/parse</td></tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>utf8</td> <td>unicode/utf8</td></tr>
|
|
<tr><td>utf16</td> <td>unicode/utf16</td></tr>
|
|
</table>
|
|
|
|
<p>
|
|
Note that the package names for the old <code>cmath</code> and
|
|
<code>exp/template/html</code> packages have changed to <code>cmplx</code>
|
|
and <code>template</code>.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
Running <code>go fix</code> will update all imports and package renames for packages that
|
|
remain inside the standard repository. Programs that import packages
|
|
that are no longer in the standard repository will need to be edited
|
|
by hand.
|
|
<br>
|
|
<font color="red">TODO: go fix should warn about deletions.</font>
|
|
</p>
|
|
|
|
<h3 id="exp">The package tree exp</h3>
|
|
|
|
<p>
|
|
Because they are not standardized, the packages under the <code>exp</code> directory will not be available in the
|
|
standard Go 1 release distributions, although they will be available in source code form
|
|
in <a href="http://code.google.com/p/go/">the repository</a> for
|
|
developers who wish to use them.
|
|
</p>
|
|
|
|
<p>
|
|
Several packages have moved under <code>exp</code> at the time of Go 1's release:
|
|
</p>
|
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|
|
<ul>
|
|
<li><code>ebnf</code></li>
|
|
<li><code>go/types</code></li>
|
|
<li><code>os/signal</code></li>
|
|
</ul>
|
|
|
|
<p>
|
|
All these packages are available under the same names, with the prefix <code>exp/</code>: <code>exp/ebnf</code> etc.
|
|
</p>
|
|
|
|
<p>
|
|
Also, the <code>utf8.String</code> type has been moved to its own package, <code>exp/utf8string</code>.
|
|
</p>
|
|
|
|
<p>
|
|
Finally, the <code>gotype</code> command now resides in <code>exp/gotype</code>, while
|
|
<code>ebnflint</code> is now in <code>exp/ebnflint</code>.
|
|
If they are installed, they now reside in <code>$GOROOT/bin/tool</code>.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
Code that uses packages in <code>exp</code> will need to be updated by hand,
|
|
or else compiled from an installation that has <code>exp</code> available.
|
|
The go fix tool or the compiler will complain about such uses.
|
|
<br>
|
|
<font color="red">TODO: go fix should warn about such uses.</font>
|
|
</p>
|
|
|
|
<h3 id="old">The package tree old</h3>
|
|
|
|
<p>
|
|
Because they are deprecated, the packages under the <code>old</code> directory will not be available in the
|
|
standard Go 1 release distributions, although they will be available in source code form for
|
|
developers who wish to use them.
|
|
</p>
|
|
|
|
<p>
|
|
The packages in their new locations are:
|
|
</p>
|
|
|
|
<ul>
|
|
<li><code>old/netchan</code></li>
|
|
<li><code>old/regexp</code></li>
|
|
<li><code>old/template</code></li>
|
|
</ul>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
Code that uses packages now in <code>old</code> will need to be updated by hand,
|
|
or else compiled from an installation that has <code>old</code> available.
|
|
The go fix tool will warn about such uses.
|
|
<br>
|
|
<font color="red">TODO: go fix should warn about such uses.</font>
|
|
</p>
|
|
|
|
<h3 id="deleted">Deleted packages</h3>
|
|
|
|
<p>
|
|
Go 1 deletes several packages outright:
|
|
</p>
|
|
|
|
<ul>
|
|
<li><code>container/vector</code></li>
|
|
<li><code>exp/datafmt</code></li>
|
|
<li><code>go/typechecker</code></li>
|
|
<li><code>try</code></li>
|
|
</ul>
|
|
|
|
<p>
|
|
and also the command <code>gotry</code>.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
Code that uses <code>container/vector</code> should be updated to use
|
|
slices directly. See
|
|
<a href="http://code.google.com/p/go-wiki/wiki/SliceTricks">the Go
|
|
Language Community Wiki</a> for some suggestions.
|
|
Code that uses the other packages (there should be almost zero) will need to be rethought.
|
|
<br>
|
|
<font color="red">TODO: go fix should warn such uses.</font>
|
|
</p>
|
|
|
|
<h3 id="subrepo">Packages moving to subrepositories</h3>
|
|
|
|
<p>
|
|
Go 1 has moved a number of packages into sub-repositories of
|
|
<a href="http://code.google.com/p/go/">the main Go repository</a>.
|
|
This table lists the old and new import paths:
|
|
|
|
<table class="codetable" frame="border" summary="Sub-repositories">
|
|
<colgroup align="left" width="40%"></colgroup>
|
|
<colgroup align="left" width="60%"></colgroup>
|
|
<tr>
|
|
<th align="left">Old</th>
|
|
<th align="left">New</th>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>crypto/bcrypt</td> <td>code.google.com/p/go.crypto/bcrypt</tr>
|
|
<tr><td>crypto/blowfish</td> <td>code.google.com/p/go.crypto/blowfish</tr>
|
|
<tr><td>crypto/cast5</td> <td>code.google.com/p/go.crypto/cast5</tr>
|
|
<tr><td>crypto/md4</td> <td>code.google.com/p/go.crypto/md4</tr>
|
|
<tr><td>crypto/ocsp</td> <td>code.google.com/p/go.crypto/ocsp</tr>
|
|
<tr><td>crypto/openpgp</td> <td>code.google.com/p/go.crypto/openpgp</tr>
|
|
<tr><td>crypto/openpgp/armor</td> <td>code.google.com/p/go.crypto/openpgp/armor</tr>
|
|
<tr><td>crypto/openpgp/elgamal</td> <td>code.google.com/p/go.crypto/openpgp/elgamal</tr>
|
|
<tr><td>crypto/openpgp/errors</td> <td>code.google.com/p/go.crypto/openpgp/errors</tr>
|
|
<tr><td>crypto/openpgp/packet</td> <td>code.google.com/p/go.crypto/openpgp/packet</tr>
|
|
<tr><td>crypto/openpgp/s2k</td> <td>code.google.com/p/go.crypto/openpgp/s2k</tr>
|
|
<tr><td>crypto/ripemd160</td> <td>code.google.com/p/go.crypto/ripemd160</tr>
|
|
<tr><td>crypto/twofish</td> <td>code.google.com/p/go.crypto/twofish</tr>
|
|
<tr><td>crypto/xtea</td> <td>code.google.com/p/go.crypto/xtea</tr>
|
|
<tr><td>exp/ssh</td> <td>code.google.com/p/go.crypto/ssh</tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>image/bmp</td> <td>code.google.com/p/go.image/bmp</tr>
|
|
<tr><td>image/tiff</td> <td>code.google.com/p/go.image/tiff</tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>net/dict</td> <td>code.google.com/p/go.net/dict</tr>
|
|
<tr><td>net/websocket</td> <td>code.google.com/p/go.net/websocket</tr>
|
|
<tr><td>exp/spdy</td> <td>code.google.com/p/go.net/spdy</tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>encoding/git85</td> <td>code.google.com/p/go.codereview/git85</tr>
|
|
<tr><td>patch</td> <td>code.google.com/p/go.codereview/patch</tr>
|
|
</table>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
Running <code>go fix</code> will update imports of these packages to use the new import paths.
|
|
Installations that depend on these packages will need to install them using
|
|
a <code>go install</code> command.
|
|
</p>
|
|
|
|
<h2 id="major">Major changes to the library</h2>
|
|
|
|
<p>
|
|
This section describes significant changes to the core libraries, the ones that
|
|
affect the most programs.
|
|
</p>
|
|
|
|
<h3 id="errors">The error type and errors package</h3>
|
|
|
|
<p>
|
|
As mentioned above, Go 1 introduces a new built-in interface type called <code>error</code>.
|
|
Its intent is to replace the old <code>os.Error</code> type with a more central concept.
|
|
So the widely-used <code>String</code> method does not cause accidental satisfaction
|
|
of the <code>error</code> interface, the <code>error</code> interface uses instead
|
|
the name <code>Error</code> for that method:
|
|
</p>
|
|
|
|
<pre>
|
|
type error interface {
|
|
Error() string
|
|
}
|
|
</pre>
|
|
|
|
<p>
|
|
The <code>fmt</code> library automatically invokes <code>Error</code>, as it already
|
|
does for <code>String</code>, for easy printing of error values.
|
|
</p>
|
|
|
|
{{code "progs/go1.go" `/START ERROR EXAMPLE/` `/END ERROR EXAMPLE/`}}
|
|
|
|
<p>
|
|
All standard packages have been updated to use the new interface; the old <code>os.Error</code> is gone.
|
|
</p>
|
|
|
|
<p>
|
|
A new package, <a href="/pkg/errors/"><code>errors</code></a>, contains the function
|
|
</p>
|
|
|
|
<pre>
|
|
func New(text string) error
|
|
</pre>
|
|
|
|
<p>
|
|
to turn a string into an error. It replaces the old <code>os.NewError</code>.
|
|
</p>
|
|
|
|
{{code "progs/go1.go" `/ErrSyntax/`}}
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
Running <code>go fix</code> will update almost all code affected by the change.
|
|
Code that defines error types with a <code>String</code> method will need to be updated
|
|
by hand to rename the methods to <code>Error</code>.
|
|
</p>
|
|
|
|
<h3 id="errno">System call errors</h3>
|
|
|
|
<p>
|
|
In Go 1, the
|
|
<a href="/pkg/syscall/"><code>syscall</code></a>
|
|
package returns an <code>error</code> for system call errors,
|
|
rather than plain integer <code>errno</code> values.
|
|
On Unix, the implementation is done by a
|
|
<a href="/pkg/syscall/#Errno"><code>syscall.Errno</code></a> type
|
|
that satisfies <code>error</code> and replaces the old <code>os.Errno</code>.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
Running <code>go fix</code> will update almost all code affected by the change.
|
|
Regardless, most code should use the <code>os</code> package
|
|
rather than <code>syscall</code> and so will be unaffected.
|
|
</p>
|
|
|
|
<h3 id="time">Time</h3>
|
|
|
|
<p>
|
|
One of the most sweeping changes in the Go 1 library is the
|
|
complete redesign of the
|
|
<a href="/pkg/time/"><code>time</code></a> package.
|
|
Instead of an integer number of nanoseconds as an <code>int64</code>,
|
|
and a separate <code>*time.Time</code> type to deal with human
|
|
units such as hours and years,
|
|
there are now two fundamental types:
|
|
<a href="/pkg/time/#Time"><code>time.Time</code></a>
|
|
(a value, so the <code>*</code> is gone), which represents a moment in time;
|
|
and <a href="/pkg/time/#Duration"><code>time.Duration</code></a>,
|
|
which represents an interval.
|
|
Both have nanosecond resolution.
|
|
A <code>Time</code> can represent any time into the ancient
|
|
past and remote future, while a <code>Duration</code> can
|
|
span plus or minus only about 290 years.
|
|
There are methods on these types, plus a number of helpful
|
|
predefined constant durations such as <code>time.Second</code>.
|
|
</p>
|
|
|
|
<p>
|
|
Among the new methods are things like
|
|
<a href="/pkg/time/#Time.Add"><code>Time.Add</code></a>,
|
|
which adds a <code>Duration</code> to a <code>Time</code>, and
|
|
<a href="/pkg/time/#Time.Sub"><code>Time.Sub</code></a>,
|
|
which subtracts two <code>Times</code> to yield a <code>Duration</code>.
|
|
</p>
|
|
|
|
<p>
|
|
The most important semantic change is that the Unix epoch (Jan 1, 1970) is now
|
|
relevant only for those functions and methods that mention Unix:
|
|
<a href="/pkg/time/#Unix"><code>time.Unix</code></a>
|
|
and the <a href="/pkg/time/#Time.Unix"><code>Unix</code></a>
|
|
and <a href="/pkg/time/#Time.UnixNano"><code>UnixNano</code></a> methods
|
|
of the <code>Time</code> type.
|
|
In particular,
|
|
<a href="/pkg/time/#Now"><code>time.Now</code></a>
|
|
returns a <code>time.Time</code> value rather than, in the old
|
|
API, an integer nanosecond count since the Unix epoch.
|
|
</p>
|
|
|
|
{{code "progs/go1.go" `/sleepUntil/` `/^}/`}}
|
|
|
|
<p>
|
|
The new types, methods, and constants have been propagated through
|
|
all the standard packages that use time, such as <code>os</code> and
|
|
its representation of file time stamps.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
The <code>go fix</code> tool will update many uses of the old <code>time</code> package to use the new
|
|
types and methods, although it does not replace values such as <code>1e9</code>
|
|
representing nanoseconds per second.
|
|
Also, because of type changes in some of the values that arise,
|
|
some of the expressions rewritten by the fix tool may require
|
|
further hand editing; in such cases the rewrite will include
|
|
the correct function or method for the old functionality, but
|
|
may have the wrong type or require further analysis.
|
|
</p>
|
|
|
|
<h2 id="minor">Minor changes to the library</h2>
|
|
|
|
<p>
|
|
This section describes smaller changes, such as those to less commonly
|
|
used packages or that affect
|
|
few programs beyond the need to run <code>go fix</code>.
|
|
This category includes packages that are new in Go 1.
|
|
</p>
|
|
|
|
<h3 id="bufio">The bufio package</h3>
|
|
|
|
<p>
|
|
In Go 1, <a href="/pkg/bufio/#NewReaderSize"><code>bufio.NewReaderSize</code></a>
|
|
and
|
|
<a href="/pkg/bufio/#NewWriterSize"><code>bufio.NewWriterSize</code></a>
|
|
functions no longer return an error for invalid sizes.
|
|
If the argument size is too small or invalid, it is adjusted.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
What little code is affected will be caught by the compiler and must be updated by hand.
|
|
</p>
|
|
|
|
<h3 id="crypto_elliptic">The crypto/elliptic package</h3>
|
|
|
|
<p>
|
|
In Go 1, <a href="/pkg/crypto/elliptic/#Curve"><code>elliptic.Curve</code></a>
|
|
has been made an interface to permit alternative implementations. The curve
|
|
parameters have been moved to the
|
|
<a href="/pkg/crypto/elliptic/#CurveParams"><code>elliptic.CurveParams</code></a>
|
|
structure.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
Existing users of <code>*elliptic.Curve</code> will need to change to
|
|
simply <code>elliptic.Curve</code>. Calls to <code>Marshal</code>,
|
|
<code>Unmarshal</code> and <code>GenerateKey</code> are now functions
|
|
in <code>crypto/elliptic</code> that take an <code>elliptic.Curve</code>
|
|
as their first argument.
|
|
</p>
|
|
|
|
<h3 id="crypto_hmac">The crypto/hmac package</h3>
|
|
|
|
<p>
|
|
In Go 1, the hash-specific functions, such as <code>hmac.NewMD5</code>, have
|
|
been removed from <code>crypto/hmac</code>. Instead, <code>hmac.New</code> takes
|
|
a function that returns a <code>hash.Hash</code>, such as <code>md5.New</code>.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
Running <code>go fix</code> will perform the needed changes.
|
|
</p>
|
|
|
|
<h3 id="crypto_x509">The crypto/x509 package</h3>
|
|
|
|
<p>
|
|
In Go 1, the
|
|
<a href="/pkg/crypto/x509/#CreateCertificate"><code>CreateCertificate</code></a>
|
|
and
|
|
<a href="/pkg/crypto/x509/#CreateCRL"><code>CreateCRL</code></a>
|
|
functions in <code>crypto/x509</code> have been altered to take an
|
|
<code>interface{}</code> where they previously took a <code>*rsa.PublicKey</code>
|
|
or <code>*rsa.PrivateKey</code>. This will allow other public key algorithms
|
|
to be implemented in the future.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
No changes will be needed.
|
|
</p>
|
|
|
|
<h3 id="encoding_binary">The encoding/binary package</h3>
|
|
|
|
<p>
|
|
In Go 1, the <code>binary.TotalSize</code> function has been replaced by
|
|
<a href="/pkg/encoding/binary/#Size"><code>Size</code></a>,
|
|
which takes an <code>interface{}</code> argument rather than
|
|
a <code>reflect.Value</code>.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
What little code is affected will be caught by the compiler and must be updated by hand.
|
|
</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>
|
|
In Go 1, the <code>RemoveAll</code> function has been removed.
|
|
The <code>Iter</code> function and Iter method on <code>*Map</code> have
|
|
been replaced by
|
|
<a href="/pkg/expvar/#Do"><code>Do</code></a>
|
|
and
|
|
<a href="/pkg/expvar/#Map.Do"><code>(*Map).Do</code></a>.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
Most code using <code>expvar</code> will not need changing. The rare code that used
|
|
<code>Iter</code> can be updated to pass a closure to <code>Do</code> to achieve the same effect.
|
|
</p>
|
|
|
|
<h3 id="flag">The flag package</h3>
|
|
|
|
<p>
|
|
In Go 1, the interface <a href="/pkg/flag/#Value"><code>flag.Value</code></a> has changed slightly.
|
|
The <code>Set</code> method now returns an <code>error</code> instead of
|
|
a <code>bool</code> to indicate success or failure.
|
|
</p>
|
|
|
|
<p>
|
|
There is also a new kind of flag, <code>Duration</code>, to support argument
|
|
values specifying time intervals.
|
|
Values for such flags must be given units, just as <code>time.Duration</code>
|
|
formats them: <code>10s</code>, <code>1h30m</code>, etc.
|
|
</p>
|
|
|
|
{{code "progs/go1.go" `/timeout/`}}
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
Programs that implement their own flags will need minor manual fixes to update their
|
|
<code>Set</code> methods.
|
|
The <code>Duration</code> flag is new and affects no existing code.
|
|
</p>
|
|
|
|
|
|
<h3 id="go">The go/* packages</h3>
|
|
|
|
<p>
|
|
Several packages under <code>go</code> have slightly revised APIs.
|
|
</p>
|
|
|
|
<p>
|
|
The modes <code>AllowIllegalChars</code> and <code>InsertSemis</code> have been removed
|
|
from the <a href="/pkg/go/scanner/"><code>go/scanner</code></a> package. They were mostly
|
|
useful for scanning text other then Go source files. Instead, the
|
|
<a href="/pkg/text/scanner/"><code>text/scanner</code></a> package should be used
|
|
for that purpose.
|
|
</p>
|
|
|
|
<p>
|
|
The <a href="/pkg/go/scanner/#ErrorHandler"><code>ErrorHandler</code></a> provided
|
|
to the scanner's <a href="/pkg/go/scanner/#Scanner.Init"><code>Init</code></a> method is
|
|
now simply a function rather than an interface. The <code>ErrorVector</code> type has
|
|
been removed in favor of the (existing) <a href="/pkg/go/scanner/#ErrorList"><code>ErrorList</code></a>
|
|
type, and the <code>ErrorVector</code> methods have been migrated. Instead of embedding
|
|
an <code>ErrorVector</code> in a client of the scanner, now a client should maintain
|
|
an <code>ErrorList</code>.
|
|
</p>
|
|
|
|
<p>
|
|
The set of parse functions provided by the <a href="/pkg/go/parser/"><code>go/parser</code></a>
|
|
package has been reduced to the primary parse function
|
|
<a href="/pkg/go/parser/#ParseFile"><code>ParseFile</code></a>, and a couple of
|
|
convenience functions <a href="/pkg/go/parser/#ParseDir"><code>ParseDir</code></a>
|
|
and <a href="/pkg/go/parser/#ParseExpr"><code>ParseExpr</code></a>.
|
|
</p>
|
|
|
|
<p>
|
|
The type names of the <a href="/pkg/go/doc/"><code>go/doc</code></a> package have been
|
|
streamlined by removing the <code>Doc</code> suffix: <code>PackageDoc</code>
|
|
is now <code>Package</code>, <code>ValueDoc</code> is <code>Value</code>, etc.
|
|
Also, all types now consistently have a <code>Name</code> field (or <code>Names</code>,
|
|
in the case of type <code>Value</code>) and <code>Type.Factories</code> has become
|
|
<code>Type.Funcs</code>.
|
|
Instead of calling <code>doc.NewPackageDoc(pkg, importpath)</code>,
|
|
documentation for a package is created with:
|
|
</p>
|
|
|
|
<pre>
|
|
doc.New(pkg, importpath, mode)
|
|
</pre>
|
|
|
|
<p>
|
|
where the new <code>mode</code> parameter specifies the operation mode:
|
|
if set to <a href="/pkg/go/doc/#AllDecls"><code>AllDecls</code></a>, all declarations
|
|
(not just exported ones) are considered.
|
|
The function <code>NewFileDoc</code> was removed, and the function
|
|
<code>CommentText</code> has become the method
|
|
<a href="/pkg/go/ast/#Text"><code>Text</code></a> of
|
|
<a href="/pkg/go/ast/#CommentGroup"><code>ast.CommentGroup</code></a>.
|
|
</p>
|
|
|
|
<p>
|
|
In package <a href="/pkg/go/token/"><code>go/token</code></a>, the
|
|
<a href="/pkg/go/token/#FileSet"><code>token.FileSet</code></a> method <code>Files</code>
|
|
(which originally returned a channel of <code>*token.File</code>s) has been replaced
|
|
with the iterator <a href="/pkg/go/token/#FileSet.Iterate"><code>Iterate</code></a> that
|
|
accepts a function argument instead.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
Code that uses packages in <code>go</code> will have to be updated by hand; the
|
|
compiler will reject incorrect uses. Templates used in conjuction with any of the
|
|
<code>go/doc</code> types may need manual fixes; the renamed fields will lead
|
|
to run-time errors.
|
|
</p>
|
|
|
|
<h3 id="hash">The hash package</h3>
|
|
|
|
<p>
|
|
In Go 1, the definition of <a href="/pkg/hash/#Hash"><code>hash.Hash</code></a> includes
|
|
a new method, <code>BlockSize</code>. This new method is used primarily in the
|
|
cryptographic libraries.
|
|
</p>
|
|
|
|
<p>
|
|
The <code>Sum</code> method of the
|
|
<a href="/pkg/hash/#Hash"><code>hash.Hash</code></a> interface now takes a
|
|
<code>[]byte</code> argument, to which the hash value will be appended.
|
|
The previous behavior can be recreated by adding a <code>nil</code> argument to the call.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
Existing implementations of <code>hash.Hash</code> will need to add a
|
|
<code>BlockSize</code> method. Hashes that process the input one byte at
|
|
a time can implement <code>BlockSize</code> to return 1.
|
|
Running <code>go fix</code> will update calls to the <code>Sum</code> methods of the various
|
|
implementations of <code>hash.Hash</code>.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
Since the package's functionality is new, no updating is necessary.
|
|
</p>
|
|
|
|
<h3 id="http">The http package</h3>
|
|
|
|
<p>
|
|
In Go 1 the <a href="/pkg/net/http/"><code>http</code></a> package is refactored,
|
|
putting some of the utilities into a
|
|
<a href="/pkg/net/httputil/"><code>httputil</code></a> subdirectory.
|
|
These pieces are only rarely needed by HTTP clients.
|
|
The affected items are:
|
|
</p>
|
|
|
|
<ul>
|
|
<li>ClientConn</li>
|
|
<li>DumpRequest</li>
|
|
<li>DumpRequest</li>
|
|
<li>DumpRequestOut</li>
|
|
<li>DumpResponse</li>
|
|
<li>NewChunkedReader</li>
|
|
<li>NewChunkedWriter</li>
|
|
<li>NewClientConn</li>
|
|
<li>NewProxyClientConn</li>
|
|
<li>NewServerConn</li>
|
|
<li>NewSingleHostReverseProxy</li>
|
|
<li>ReverseProxy</li>
|
|
<li>ServerConn</li>
|
|
</ul>
|
|
|
|
<p>
|
|
The <code>Request.RawURL</code> field has been removed; it was a
|
|
historical artifact.
|
|
</p>
|
|
|
|
<p>
|
|
The <code>Handle</code> and <code>HandleFunc</code>
|
|
functions, and the similarly-named methods of <code>ServeMux</code>,
|
|
now panic if an attempt is made to register the same pattern twice.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
Running <code>go fix</code> will update the few programs that are affected except for
|
|
uses of <code>RawURL</code>, which must be fixed by hand.
|
|
</p>
|
|
|
|
<h3 id="image">The image package</h3>
|
|
|
|
<p>
|
|
The <a href="/pkg/image/"><code>image</code></a> package has had a number of
|
|
minor changes, rearrangements and renamings.
|
|
</p>
|
|
|
|
<p>
|
|
Most of the color handling code has been moved into its own package,
|
|
<a href="/pkg/image/color/"><code>image/color</code></a>.
|
|
For the elements that moved, a symmetry arises; for instance,
|
|
each pixel of an
|
|
<a href="/pkg/image/#RGBA"><code>image.RGBA</code></a>
|
|
is a
|
|
<a href="/pkg/image/color/#RGBA"><code>color.RGBA</code></a>.
|
|
</p>
|
|
|
|
<p>
|
|
The old <code>image/ycbcr</code> package has been folded, with some
|
|
renamings, into the
|
|
<a href="/pkg/image/"><code>image</code></a>
|
|
and
|
|
<a href="/pkg/image/color/"><code>image/color</code></a>
|
|
packages.
|
|
</p>
|
|
|
|
<p>
|
|
The old <code>image.ColorImage</code> type is still in the <code>image</code>
|
|
package but has been renamed
|
|
<a href="/pkg/image/#Uniform"><code>image.Uniform</code></a>,
|
|
while <code>image.Tiled</code> has been removed.
|
|
</p>
|
|
|
|
<p>
|
|
This table lists the renamings.
|
|
</p>
|
|
|
|
<table class="codetable" frame="border" summary="image renames">
|
|
<colgroup align="left" width="50%"></colgroup>
|
|
<colgroup align="left" width="50%"></colgroup>
|
|
<tr>
|
|
<th align="left">Old</th>
|
|
<th align="left">New</th>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>image.Color</td> <td>color.Color</td></tr>
|
|
<tr><td>image.ColorModel</td> <td>color.Model</td></tr>
|
|
<tr><td>image.ColorModelFunc</td> <td>color.ModelFunc</td></tr>
|
|
<tr><td>image.PalettedColorModel</td> <td>color.Palette</td></tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>image.RGBAColor</td> <td>color.RGBA</td></tr>
|
|
<tr><td>image.RGBA64Color</td> <td>color.RGBA64</td></tr>
|
|
<tr><td>image.NRGBAColor</td> <td>color.NRGBA</td></tr>
|
|
<tr><td>image.NRGBA64Color</td> <td>color.NRGBA64</td></tr>
|
|
<tr><td>image.AlphaColor</td> <td>color.Alpha</td></tr>
|
|
<tr><td>image.Alpha16Color</td> <td>color.Alpha16</td></tr>
|
|
<tr><td>image.GrayColor</td> <td>color.Gray</td></tr>
|
|
<tr><td>image.Gray16Color</td> <td>color.Gray16</td></tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>image.RGBAColorModel</td> <td>color.RGBAModel</td></tr>
|
|
<tr><td>image.RGBA64ColorModel</td> <td>color.RGBA64Model</td></tr>
|
|
<tr><td>image.NRGBAColorModel</td> <td>color.NRGBAModel</td></tr>
|
|
<tr><td>image.NRGBA64ColorModel</td> <td>color.NRGBA64Model</td></tr>
|
|
<tr><td>image.AlphaColorModel</td> <td>color.AlphaModel</td></tr>
|
|
<tr><td>image.Alpha16ColorModel</td> <td>color.Alpha16Model</td></tr>
|
|
<tr><td>image.GrayColorModel</td> <td>color.GrayModel</td></tr>
|
|
<tr><td>image.Gray16ColorModel</td> <td>color.Gray16Model</td></tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>ycbcr.RGBToYCbCr</td> <td>color.RGBToYCbCr</td></tr>
|
|
<tr><td>ycbcr.YCbCrToRGB</td> <td>color.YCbCrToRGB</td></tr>
|
|
<tr><td>ycbcr.YCbCrColorModel</td> <td>color.YCbCrModel</td></tr>
|
|
<tr><td>ycbcr.YCbCrColor</td> <td>color.YCbCr</td></tr>
|
|
<tr><td>ycbcr.YCbCr</td> <td>image.YCbCr</td></tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>ycbcr.SubsampleRatio444</td> <td>image.YCbCrSubsampleRatio444</td></tr>
|
|
<tr><td>ycbcr.SubsampleRatio422</td> <td>image.YCbCrSubsampleRatio422</td></tr>
|
|
<tr><td>ycbcr.SubsampleRatio420</td> <td>image.YCbCrSubsampleRatio420</td></tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>image.ColorImage</td> <td>image.Uniform</td></tr>
|
|
</table>
|
|
|
|
<p>
|
|
The image package's <code>New</code> functions
|
|
(<a href="/pkg/image/#NewRGBA"><code>NewRGBA</code></a>,
|
|
<a href="/pkg/image/#NewRGBA64"><code>NewRGBA64</code></a>, etc.)
|
|
take an <a href="/pkg/image/#Rectangle"><code>image.Rectangle</code></a> as an argument
|
|
instead of four integers.
|
|
</p>
|
|
|
|
<p>
|
|
Finally, there are new predefined <code>color.Color</code> variables
|
|
<a href="/pkg/image/color/#Black"><code>color.Black</code></a>,
|
|
<a href="/pkg/image/color/#White"><code>color.White</code></a>,
|
|
<a href="/pkg/image/color/#Opaque"><code>color.Opaque</code></a>
|
|
and
|
|
<a href="/pkg/image/color/#Transparent"><code>color.Transparent</code></a>.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
Running <code>go fix</code> will update almost all code affected by the change.
|
|
</p>
|
|
|
|
<h3 id="log_syslog">The log/syslog package</h3>
|
|
|
|
<p>
|
|
In Go 1, the <a href="/pkg/log/syslog/#NewLogger"><code>syslog.NewLogger</code></a>
|
|
function returns an error as well as a <code>log.Logger</code>.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
What little code is affected will be caught by the compiler and must be updated by hand.
|
|
</p>
|
|
|
|
<h3 id="mime">The mime package</h3>
|
|
|
|
<p>
|
|
In Go 1, the <a href="/pkg/mime/#FormatMediaType"><code>FormatMediaType</code></a> function
|
|
of the <code>mime</code> package has been simplified to make it
|
|
consistent with
|
|
<a href="/pkg/mime/#ParseMediaType"><code>ParseMediaType</code></a>.
|
|
It now takes <code>"text/html"</code> rather than <code>"text"</code> and <code>"html"</code>.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
What little code is affected will be caught by the compiler and must be updated by hand.
|
|
</p>
|
|
|
|
<h3 id="net">The net package</h3>
|
|
|
|
<p>
|
|
In Go 1, the various <code>SetTimeout</code>,
|
|
<code>SetReadTimeout</code>, and <code>SetWriteTimeout</code> methods
|
|
have been replaced with
|
|
<a href="/pkg/net/#IPConn.SetDeadline"><code>SetDeadline</code></a>,
|
|
<a href="/pkg/net/#IPConn.SetReadDeadline"><code>SetReadDeadline</code></a>, and
|
|
<a href="/pkg/net/#IPConn.SetWriteDeadline"><code>SetWriteDeadline</code></a>,
|
|
respectively. Rather than taking a timeout value in nanoseconds that
|
|
apply to any activity on the connection, the new methods set an
|
|
absolute deadline (as a <code>time.Time</code> value) after which
|
|
reads and writes will time out and no longer block.
|
|
</p>
|
|
|
|
<p>
|
|
There are also new functions
|
|
<a href="/pkg/net/#DialTimeout"><code>net.DialTimeout</code></a>
|
|
to simplify timing out dialing a network address and
|
|
<a href="/pkg/net/#ListenMulticastUDP"><code>net.ListenMulticastUDP</code></a>
|
|
to allow multicast UDP to listen concurrently across multiple listeners.
|
|
The <code>net.ListenMulticastUDP</code> function replaces the old
|
|
<code>JoinGroup</code> and <code>LeaveGroup</code> methods.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
Code that uses the old methods will fail to compile and must be updated by hand.
|
|
The semantic change makes it difficult for the fix tool to update automatically.
|
|
</p>
|
|
|
|
<h3 id="os">The os package</h3>
|
|
|
|
<p>The <code>Time</code> function has been removed; callers should use
|
|
the <a href="/pkg/time/#Time"><code>Time</code></a> type from the
|
|
<code>time</code> package.</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
Code that uses <code>os.Time</code> will fail to compile and must be updated by hand.
|
|
</p>
|
|
|
|
<h4 id="os_fileinfo">The os.FileInfo type</h4>
|
|
|
|
<p>
|
|
Go 1 redefines the <a href="/pkg/os/#FileInfo"><code>os.FileInfo</code></a> type,
|
|
changing it from a struct to an interface:
|
|
</p>
|
|
|
|
<pre>
|
|
type FileInfo interface {
|
|
Name() string // base name of the file
|
|
Size() int64 // length in bytes
|
|
Mode() FileMode // file mode bits
|
|
ModTime() time.Time // modification time
|
|
IsDir() bool // abbreviation for Mode().IsDir()
|
|
}
|
|
</pre>
|
|
|
|
<p>
|
|
The file mode information has been moved into a subtype called
|
|
<a href="/pkg/os/#FileMode"><code>os.FileMode</code></a>,
|
|
a simple integer type with <code>IsDir</code>, <code>Perm</code>, and <code>String</code>
|
|
methods.
|
|
</p>
|
|
|
|
<p>
|
|
The system-specific details of file modes and properties such as (on Unix)
|
|
i-number have been removed from <code>FileInfo</code> altogether.
|
|
Instead, each operating system's <code>os</code> package provides an
|
|
implementation of the <code>FileInfo</code> interface, <code>*os.FileStat</code>,
|
|
which in turn contains a <code>Sys</code> field that stores the
|
|
system-specific representation of file metadata.
|
|
For instance, to discover the i-number of a file on a Unix system, unpack
|
|
the <code>FileInfo</code> like this:
|
|
</p>
|
|
|
|
<pre>
|
|
fi, err := os.Stat("hello.go")
|
|
if err != nil {
|
|
log.Fatal(err)
|
|
}
|
|
// Make sure it's an implementation known to package os.
|
|
fileStat, ok := fi.(*os.FileStat)
|
|
if !ok {
|
|
log.Fatal("hello.go: not an os File")
|
|
}
|
|
// Now check that it's a Unix file.
|
|
unixStat, ok := fileStat.Sys.(*syscall.Stat_t)
|
|
if !ok {
|
|
log.Fatal("hello.go: not a Unix file")
|
|
}
|
|
fmt.Printf("file i-number: %d\n", unixStat.Ino)
|
|
</pre>
|
|
|
|
<p>
|
|
Assuming (which is unwise) that <code>"hello.go"</code> is a Unix file,
|
|
the i-number expression could be contracted to
|
|
</p>
|
|
|
|
<pre>
|
|
fi.(*os.FileStat).Sys.(*syscall.Stat_t).Ino
|
|
</pre>
|
|
|
|
<p>
|
|
The vast majority of uses of <code>FileInfo</code> need only the methods
|
|
of the standard interface.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
Running <code>go fix</code> will update code that uses the old equivalent of the current <code>os.FileInfo</code>
|
|
and <code>os.FileMode</code> API.
|
|
Code that needs system-specific file details will need to be updated by hand.
|
|
</p>
|
|
|
|
<h3 id="path_filepath">The path/filepath package</h3>
|
|
|
|
<p>
|
|
In Go 1, the <a href="/pkg/path/filepath/#Walk"><code>Walk</code></a> function of the
|
|
<code>path/filepath</code> package
|
|
has been changed to take a function value of type
|
|
<a href="/pkg/path/filepath/#WalkFunc"><code>WalkFunc</code></a>
|
|
instead of a <code>Visitor</code> interface value.
|
|
<code>WalkFunc</code> unifies the handling of both files and directories.
|
|
</p>
|
|
|
|
<pre>
|
|
type WalkFunc func(path string, info *os.FileInfo, err os.Error) os.Error
|
|
</pre>
|
|
|
|
<p>
|
|
The <code>WalkFunc</code> function will be called even for files or directories that could not be opened;
|
|
in such cases the error argument will describe the failure.
|
|
If a directory's contents are to be skipped,
|
|
the function should return the value <code>SkipDir</code>.
|
|
</p>
|
|
|
|
<p>
|
|
<font color="red">TODO: add an example?</font>
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
The change simplifies most code but has subtle consequences, so affected programs
|
|
will need to be updated by hand.
|
|
The compiler will catch code using the old interface.
|
|
</p>
|
|
|
|
<h3 id="runtime">The runtime package</h3>
|
|
|
|
<p>
|
|
The <code>runtime</code> package in Go 1 includes a new niladic function,
|
|
<a href="/pkg/runtime/#NumCPU"><code>runtime.NumCPU</code></a>, that returns the number of CPUs available
|
|
for parallel execution, as reported by the operating system kernel.
|
|
Its value can inform the setting of <code>GOMAXPROCS</code>.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
No existing code is affected.
|
|
</p>
|
|
|
|
<h3 id="strconv">The strconv package</h3>
|
|
|
|
<p>
|
|
In Go 1, the
|
|
<a href="/pkg/strconv/"><code>strconv</code></a>
|
|
package has been significantly reworked to make it more Go-like and less C-like,
|
|
although <code>Atoi</code> lives on (it's similar to
|
|
<code>int(ParseInt(x, 10, 0))</code>, as does
|
|
<code>Itoa(x)</code> (<code>FormatInt(int64(x), 10)</code>).
|
|
There are also new variants of some of the functions that append to byte slices rather than
|
|
return strings, to allow control over allocation.
|
|
</p>
|
|
|
|
<p>
|
|
This table summarizes the renamings; see the
|
|
<a href="/pkg/strconv/">package documentation</a>
|
|
for full details.
|
|
</p>
|
|
|
|
<table class="codetable" frame="border" summary="strconv renames">
|
|
<colgroup align="left" width="50%"></colgroup>
|
|
<colgroup align="left" width="50%"></colgroup>
|
|
<tr>
|
|
<th align="left">Old call</th>
|
|
<th align="left">New call</th>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>Atob(x)</td> <td>ParseBool(x)</td></tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>Atof32(x)</td> <td>ParseFloat(x, 32)§</td></tr>
|
|
<tr><td>Atof64(x)</td> <td>ParseFloat(x, 64)</td></tr>
|
|
<tr><td>AtofN(x, n)</td> <td>ParseFloat(x, n)</td></tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>Atoi(x)</td> <td>Atoi(x)</td></tr>
|
|
<tr><td>Atoi(x)</td> <td>ParseInt(x, 10, 0)§</td></tr>
|
|
<tr><td>Atoi64(x)</td> <td>ParseInt(x, 10, 64)</td></tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>Atoui(x)</td> <td>ParseUint(x, 10, 0)§</td></tr>
|
|
<tr><td>Atoi64(x)</td> <td>ParseInt(x, 10, 64)</td></tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>Btoi64(x, b)</td> <td>ParseInt(x, b, 64)</td></tr>
|
|
<tr><td>Btoui64(x, b)</td> <td>ParseUint(x, b, 64)</td></tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>Btoa(x)</td> <td>FormatBool(x)</td></tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>Ftoa32(x, f, p)</td> <td>FormatFloat(x, float64(f), p, 32)</td></tr>
|
|
<tr><td>Ftoa64(x, f, p)</td> <td>FormatFloat(x, f, p, 64)</td></tr>
|
|
<tr><td>FtoaN(x, f, p, n)</td> <td>FormatFloat(x, f, p, n)</td></tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>Itoa(x)</td> <td>Itoa(x)</td></tr>
|
|
<tr><td>Itoa(x)</td> <td>FormatInt(int64(x), 10)</td></tr>
|
|
<tr><td>Itoa64(x)</td> <td>FormatInt(x, 10)</td></tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>Itob(x, b)</td> <td>FormatInt(int64(x), b)</td></tr>
|
|
<tr><td>Itob64(x, b)</td> <td>FormatInt(x, b)</td></tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>Uitoa(x)</td> <td>FormatUint(uint64(x), 10)</td></tr>
|
|
<tr><td>Uitoa64(x)</td> <td>FormatUint(x, 10)</td></tr>
|
|
<tr>
|
|
<td colspan="2"><hr></td>
|
|
</tr>
|
|
<tr><td>Uitob(x, b)</td> <td>FormatUint(uint64(x), b)</td></tr>
|
|
<tr><td>Uitob64(x, b)</td> <td>FormatUint(x, b)</td></tr>
|
|
</table>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
Running <code>go fix</code> will update almost all code affected by the change.
|
|
<br>
|
|
§ <code>Atoi</code> persists but <code>Atoui</code> and <code>Atof32</code> do not, so
|
|
they may require
|
|
a cast that must be added by hand; the go fix tool will warn about it.
|
|
</p>
|
|
|
|
|
|
<h3 id="testing">The testing package</h3>
|
|
|
|
<p>
|
|
The testing package has a type, <code>B</code>, passed as an argument to benchmark functions.
|
|
In Go 1, <code>B</code> has new methods, analogous to those of <code>T</code>, enabling
|
|
logging and failure reporting.
|
|
</p>
|
|
|
|
{{code "progs/go1.go" `/func.*Benchmark/` `/^}/`}}
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
Existing code is unaffected, although benchmarks that use <code>println</code>
|
|
or <code>panic</code> should be updated to use the new methods.
|
|
</p>
|
|
|
|
<h3 id="url">The url package</h3>
|
|
|
|
<p>
|
|
In Go 1 several fields from the <a href="/pkg/net/url/#URL"><code>url.URL</code></a> type
|
|
were removed or replaced.
|
|
</p>
|
|
|
|
<p>
|
|
The <a href="/pkg/net/url/#URL.String"><code>String</code></a> method now
|
|
predictably rebuilds an encoded URL string using all of <code>URL</code>'s
|
|
fields as necessary. The resulting string will also no longer have
|
|
passwords escaped.
|
|
</p>
|
|
|
|
<p>
|
|
The <code>Raw</code> field has been removed. In most cases the <code>String</code>
|
|
method may be used in its place.
|
|
</p>
|
|
|
|
<p>
|
|
The old <code>RawUserinfo</code> field is replaced by the <code>User</code>
|
|
field, of type <a href="/pkg/net/url/#Userinfo"><code>*net.Userinfo</code></a>.
|
|
Values of this type may be created using the new <a href="/pkg/net/url/#User"><code>net.User</code></a>
|
|
and <a href="/pkg/net/url/#UserPassword"><code>net.UserPassword</code></a>
|
|
functions. The <code>EscapeUserinfo</code> and <code>UnescapeUserinfo</code>
|
|
functions are also gone.
|
|
</p>
|
|
|
|
<p>
|
|
The <code>RawAuthority</code> field has been removed. The same information is
|
|
available in the <code>Host</code> and <code>User</code> fields.
|
|
</p>
|
|
|
|
<p>
|
|
The <code>RawPath</code> field and the <code>EncodedPath</code> method have
|
|
been removed. The path information in rooted URLs (with a slash following the
|
|
schema) is now available only in decoded form in the <code>Path</code> field.
|
|
Occasionally, the encoded data may be required to obtain information that
|
|
was lost in the decoding process. These cases must be handled by accessing
|
|
the data the URL was built from.
|
|
</p>
|
|
|
|
<p>
|
|
URLs with non-rooted paths, such as <code>"mailto:dev@golang.org?subject=Hi"</code>,
|
|
are also handled differently. The <code>OpaquePath</code> boolean field has been
|
|
removed and a new <code>Opaque</code> string field introduced to hold the encoded
|
|
path for such URLs. In Go 1, the cited URL parses as:
|
|
</p>
|
|
|
|
<pre>
|
|
URL{
|
|
Scheme: "mailto",
|
|
Opaque: "dev@golang.org",
|
|
RawQuery: "subject=Hi",
|
|
}
|
|
</pre>
|
|
|
|
<p>
|
|
A new <a href="/pkg/net/url/#URL.RequestURI"><code>RequestURI</code></a> method was
|
|
added to <code>URL</code>.
|
|
</p>
|
|
|
|
<p>
|
|
<em>Updating</em>:
|
|
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>
|
|
|
|
<h2 id="go_command">The go command</h2>
|
|
|
|
<h2 id="releases">Packaged releases</h2>
|
|
|