| <!--{ |
| "Title": "Go 1 Release Notes" |
| }--> |
| {{donotedit}} |
| |
| <h2 id="introduction">Introduction to Go 1</h2> |
| |
| <p> |
| For a full explanation of the motivation and design of Go 1, see XXX. |
| Here follows a summary. |
| </p> |
| |
| <p> |
| Go 1 is intended to be a stable language and core library set that |
| will form a reliable foundation for people and organizations that |
| want to make a long-term commitment to developing in the Go programming |
| language. Go will continue to develop, but in a way that guarantees |
| code written to the Go 1 specification will continue to work. For |
| instance, Go 1 will be a supported platform on Google App Engine |
| for the next few years. Incompatible changes to the environment, |
| should they arise, will be done in a distinct version. |
| </p> |
| |
| <p> |
| This document describes the changes in the language and libraries |
| in Go 1, relative to the previous release, r60 (at the time of |
| writing, tagged as r60.3). It also explains how to update code at |
| r60 to compile and run under Go 1. Finally, it outlines the new |
| <code>go</code> command for building Go programs and the new binary |
| release process being introduced. Most of these topics have more |
| thorough presentations elsewhere; such documents are linked below. |
| </p> |
| |
| <h2 id="language">Changes to the language</h2> |
| |
| <h3 id="append">Append</h3> |
| |
| <p> |
| The <code>append</code> built-in function is variadic, so one can |
| append to a byte slice using the <code>...</code> syntax in the |
| call. |
| </p> |
| |
| {{code "progs/go1.go" `/greeting := ..byte/` `/append.*hello/`}} |
| |
| <p> |
| By analogy with the similar property of <code>copy</code>, Go 1 |
| permits a string to be appended (byte-wise) directly to a byte |
| slice; the conversion is no longer necessary: |
| </p> |
| |
| {{code "progs/go1.go" `/append.*world/`}} |
| |
| <p> |
| <em>Updating</em>: |
| This is a new feature, so existing code needs no changes. |
| </p> |
| |
| <h3 id="close">Close</h3> |
| |
| <p> |
| The <code>close</code> built-in function lets a sender tell a receiver |
| that no more data will be transmitted on the channel. In Go 1 the |
| type system enforces the directionality when possible: it is illegal |
| to call <code>close</code> on a receive-only channel: |
| </p> |
| |
| <pre> |
| var c chan int |
| var csend chan<- int = c |
| var crecv <-chan int = c |
| close(c) // legal |
| close(csend) // legal |
| close(crecv) // illegal |
| </pre> |
| |
| <p> |
| <em>Updating</em>: |
| Existing code that attempts to close a receive-only channel was |
| erroneous even before Go 1 and should be fixed. The compiler will |
| now reject such code. |
| </p> |
| |
| <h3 id="literals">Composite literals</h3> |
| |
| <p> |
| In Go 1, a composite literal of array, slice, or map type can elide the |
| type specification for the elements' initializers if they are of pointer type. |
| All four of the initializations in this example are legal; the last one was illegal before Go 1. |
| </p> |
| |
| {{code "progs/go1.go" `/type Date struct/` `/STOP/`}} |
| |
| <p> |
| <em>Updating</em>: |
| This change has no effect on existing code, but the command |
| <code>gofmt</code> <code>-s</code> applied to existing source |
| will, among other things, elide explicit element types wherever permitted. |
| </p> |
| |
| |
| <h3 id="init">Goroutines during init</h3> |
| |
| <p> |
| Go 1 allows goroutines to be created and run during initialization. |
| (They used to be created but were not run until after initialization |
| completed.) Code that uses goroutines can now be called from |
| <code>init</code> routines and global initialization expressions |
| without introducing a deadlock. |
| </p> |
| |
| {{code "progs/go1.go" `/PackageGlobal/` `/^}/`}} |
| |
| <p> |
| <em>Updating</em>: |
| This is a new feature, so existing code needs no changes, |
| although it's possible that code that depends on goroutines not starting before <code>main</code> will break. |
| There was no such code in the standard repository. |
| </p> |
| |
| <h3 id="rune">The rune type</h3> |
| |
| <p> |
| Go 1 introduces a new basic type, <code>rune</code>, to be used to represent |
| individual Unicode code points. |
| It is an alias for <code>int32</code>, analogous to <code>byte</code> |
| as an alias for <code>uint8</code>. |
| </p> |
| |
| <p> |
| Character literals such as <code>'a'</code>, <code>'語'</code>, and <code>'\u0345'</code> |
| now have default type <code>rune</code>, |
| analogous to <code>1.0</code> having default type <code>float64</code>. |
| A variable initialized to a character constant will therefore |
| have type <code>rune</code> unless otherwise specified. |
| </p> |
| |
| <p> |
| Libraries have been updated to use <code>rune</code> rather than <code>int</code> |
| when appropriate. For instance, the functions <code>unicode.ToLower</code> and |
| relatives now take and return a <code>rune</code>. |
| </p> |
| |
| {{code "progs/go1.go" `/STARTRUNE/` `/ENDRUNE/`}} |
| |
| <p> |
| <em>Updating</em>: |
| Most source code will be unaffected by this because the type inference from |
| <code>:=</code> initializers introduces the new type silently, and it propagates |
| from there. |
| Some code may get type errors that a trivial conversion will resolve. |
| </p> |
| |
| <h3 id="error">The error type</h3> |
| |
| <p> |
| Go 1 introduces a new built-in type, <code>error</code>, which has the following definition: |
| </p> |
| |
| <pre> |
| type error interface { |
| Error() string |
| } |
| </pre> |
| |
| <p> |
| Since the consequences of this type are all in the package library, |
| it is discussed <a href="#errors">below</a>. |
| </p> |
| |
| <h3 id="delete">Deleting from maps</h3> |
| |
| <p> |
| The original syntax for deleting an element in a map was: |
| </p> |
| |
| <pre> |
| m[k] = ignored, false |
| </pre> |
| |
| <p> |
| In Go 1, that syntax has gone; instead there is a new built-in |
| function, <code>delete</code>. The call |
| </p> |
| |
| {{code "progs/go1.go" `/delete\(m, k\)/`}} |
| |
| <p> |
| will delete the map entry retrieved by the expression <code>m[k]</code>. |
| There is no return value. Deleting a non-existent entry is a no-op. |
| </p> |
| |
| <p> |
| <em>Updating</em>: |
| Running <code>go fix</code> will convert expressions of the form <code>m[k] = ignored, |
| false</code> into <code>delete(m, k)</code> when it is clear that |
| the ignored value can be safely discarded from the program and |
| <code>false</code> refers to the predefined boolean constant. |
| The fix tool |
| will flag other uses of the syntax for inspection by the programmer. |
| </p> |
| |
| <h3 id="iteration">Iterating in maps</h3> |
| |
| <p> |
| In Go 1, the order in which elements are visited when iterating |
| over a map using a <code>for</code> <code>range</code> statement |
| is defined to be unpredictable, even if the same loop is run multiple |
| times with the same map. |
| Code should not assume that the elements are visited in any particular order. |
| </p> |
| |
| {{code "progs/go1.go" `/Sunday/` `/^ }/`}} |
| |
| <p> |
| <em>Updating</em>: |
| This is one change where tools cannot help. Most existing code |
| will be unaffected, but some programs may break or misbehave; we |
| recommend manual checking of all range statements over maps to |
| verify they do not depend on iteration order. There were a few such |
| examples in the standard repository; they have been fixed. |
| Note that it was already incorrect to depend on the iteration order, which |
| was unspecified. This change codifies the unpredictability. |
| </p> |
| |
| <h3 id="multiple_assignment">Multiple assignment</h3> |
| |
| <p> |
| Go 1 fully specifies the evaluation order in multiple assignment |
| statements. In particular, if the left-hand side of the assignment |
| statement contains expressions that require evaluation, such as |
| function calls or array indexing operations, these will all be done |
| using the usual left-to-right rule before any variables are assigned |
| their value. Once everything is evaluated, the actual assignments |
| proceed in left-to-right order. |
| </p> |
| |
| <p> |
| These examples illustrate the behavior. |
| </p> |
| |
| {{code "progs/go1.go" `/sa :=/` `/then sc.0. = 2/`}} |
| |
| <p> |
| <em>Updating</em>: |
| This is one change where tools cannot help, but breakage is unlikely. |
| No code in the standard repository was broken by this change, and code |
| that depended on the previous unspecified behavior was already incorrect. |
| </p> |
| |
| <h3 id="shadowing">Returns and shadowed variables</h3> |
| |
| <p> |
| A shadowed variable is one that has the same name as another variable in an inner scope. |
| In functions with named return values, |
| 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. |
| (It isn't part of the specification, because this is one area we are still exploring; |
| the situation is analogous to the compilers rejecting functions that do not end with an explicit return statement.) |
| </p> |
| |
| <p> |
| This function implicitly returns a shadowed return value and will be rejected by the compiler: |
| </p> |
| |
| <pre> |
| func Bug() (i, j, k int) { |
| for i = 0; i < 5; i++ { |
| for j := 0; j < 5; j++ { // Redeclares j. |
| k += i*j |
| if k > 100 { |
| return // Rejected: j is shadowed here. |
| } |
| } |
| } |
| return // OK: j is not shadowed here. |
| } |
| </pre> |
| |
| <p> |
| <em>Updating</em>: |
| Code that shadows return values in this way will be rejected by the compiler and will need to be fixed by hand. |
| The few cases that arose in the standard repository were mostly bugs. |
| </p> |
| |
| <h3 id="unexported">Copying structs with unexported fields</h3> |
| |
| <p> |
| Go 1 relaxes the rules about accessing structs with unexported (lower-case) fields, |
| permitting a client package to assign (and therefore copy) such a struct. |
| Of course, the client package still cannot access such fields individually. |
| </p> |
| |
| <p> |
| As an example, if package <code>p</code> includes the definitions, |
| </p> |
| |
| <pre> |
| type Struct struct { |
| Public int |
| secret int |
| } |
| func NewStruct(a int) Struct { // Note: not a pointer. |
| return Struct{a, f(a)} |
| } |
| func (s Struct) String() string { |
| return fmt.Sprintf("{%d (secret %d)}", s.Public, s.secret) |
| } |
| </pre> |
| |
| <p> |
| a package that imports <code>p</code> can assign and copy values of type |
| <code>p.Struct</code> at will. |
| Behind the scenes the unexported fields will be assigned and copied just |
| as if they were exported, |
| but the client code will never be aware of them. The code |
| </p> |
| |
| <pre> |
| import "p" |
| |
| myStruct := p.NewStruct(23) |
| copyOfMyStruct := myStruct |
| fmt.Println(myStruct, copyOfMyStruct) |
| </pre> |
| |
| <p> |
| will show that the secret field of the struct has been copied to the new value. |
| </p> |
| |
| <p> |
| <em>Updating</em>: |
| This is a new feature, so existing code needs no changes. |
| </p> |
| |
| <h3 id="equality">Equality of structs and arrays</h3> |
| |
| <p> |
| Go 1 defines equality and inequality (<code>==</code> and |
| <code>!=</code>) for struct and array values, respectively, provided |
| the elements of the data structures can themselves be compared. |
| That is, if equality is defined for all the fields of a struct (or |
| an array element), then it is defined for the struct (or array). |
| </p> |
| |
| <p> |
| As a result, structs and arrays can now be used as map keys: |
| </p> |
| |
| {{code "progs/go1.go" `/type Day struct/` `/Printf/`}} |
| |
| <p> |
| Note that equality is still undefined for slices, for which the |
| calculation is in general infeasible. Also note that the ordered |
| comparison operators (<code><</code> <code><=</code> |
| <code>></code> <code>>=</code>) are still undefined for |
| structs and arrays. |
| |
| <p> |
| <em>Updating</em>: |
| This is a new feature, so existing code needs no changes. |
| </p> |
| |
| <h3 id="funcs">Function and map equality</h3> |
| |
| <p> |
| Go 1 disallows checking for equality of functions and maps, |
| respectively, except to compare them directly to <code>nil</code>. |
| </p> |
| |
| <p> |
| <em>Updating</em>: |
| Existing code that depends on function or map equality will be |
| rejected by the compiler and will need to be fixed by hand. |
| Few programs will be affected, but the fix may require some |
| redesign. |
| </p> |
| |
| <h2 id="packages">The package hierarchy</h2> |
| |
| <p> |
| This section describes how the packages have been rearranged in Go 1. |
| Some have moved, some have been renamed, some have been deleted. |
| New packages are described in later sections. |
| </p> |
| |
| <h3 id="hierarchy">The package hierarchy</h3> |
| |
| <p> |
| Go 1 has a rearranged package hierarchy that groups related items |
| into subdirectories. For instance, <code>utf8</code> and |
| <code>utf16</code> now occupy subdirectories of <code>unicode</code>. |
| Also, <a href="#subrepo">some packages</a> have moved into |
| subrepositories of |
| <a href="http://code.google.com/p/go"><code>code.google.com/p/go</code></a> |
| while <a href="#deleted">others</a> have been deleted outright. |
| </p> |
| |
| <table class="codetable" frame="border" summary="Moved packages"> |
| <colgroup align="left" width="60%"></colgroup> |
| <colgroup align="left" width="40%"></colgroup> |
| <tr> |
| <th align="left">Old path</th> |
| <th align="left">New path</th> |
| </tr> |
| <tr> |
| <td colspan="2"><hr></td> |
| </tr> |
| <tr><td>asn1</td> <td>encoding/asn1</td></tr> |
| <tr><td>csv</td> <td>encoding/csv</td></tr> |
| <tr><td>gob</td> <td>encoding/gob</td></tr> |
| <tr><td>json</td> <td>encoding/json</td></tr> |
| <tr><td>xml</td> <td>encoding/xml</td></tr> |
| <tr> |
| <td colspan="2"><hr></td> |
| </tr> |
| <tr><td>exp/template/html</td> <td>html/template</td></tr> |
| <tr> |
| <td colspan="2"><hr></td> |
| </tr> |
| <tr><td>big</td> <td>math/big</td></tr> |
| <tr><td>cmath</td> <td>math/cmplx</td></tr> |
| <tr><td>rand</td> <td>math/rand</td></tr> |
| <tr> |
| <td colspan="2"><hr></td> |
| </tr> |
| <tr><td>http</td> <td>net/http</td></tr> |
| <tr><td>http/cgi</td> <td>net/http/cgi</td></tr> |
| <tr><td>http/fcgi</td> <td>net/http/fcgi</td></tr> |
| <tr><td>http/httptest</td> <td>net/http/httptest</td></tr> |
| <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> |
| |
| <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="bufio">The compress/flate, compress/gzip and compress/zlib packages</h3> |
| |
| <p> |
| In Go 1, the <code>NewWriterXxx</code> functions in |
| <a href="/pkg/compress/flate"><code>compress/flate</code></a>, |
| <a href="/pkg/compress/gzip"><code>compress/gzip</code></a> and |
| <a href="/pkg/compress/zlib"><code>compress/zlib</code></a> |
| all return <code>(*Writer, error)</code> if they take a compression level, |
| and <code>*Writer</code> otherwise. Package <code>gzip</code>'s |
| <code>Compressor</code> and <code>Decompressor</code> types have been renamed |
| to <code>Writer</code> and <code>Reader</code>. Package <code>flate</code>'s |
| <code>WrongValueError</code> type has been removed. |
| </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> |
| A concrete <code>Mode</code> type was introduced for configuration mode flags |
| in the packages |
| <a href="/pkg/go/scanner/"><code>go/scanner</code></a>, |
| <a href="/pkg/go/parser/"><code>go/parser</code></a>, |
| <a href="/pkg/go/printer/"><code>go/printer</code></a>, and |
| <a href="/pkg/go/doc/"><code>go/doc</code></a>. |
| </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 <a href="/pkg/go/printer/"><code>go/printer</code></a> package supports an additional |
| configuration mode <a href="/pkg/go/printer/#Mode"><code>SourcePos</code></a>; |
| if set, the printer will emit <code>//line</code> comments such that the generated |
| output contains the original source code position information. The new type |
| <a href="/pkg/go/printer/#CommentedNode"><code>CommentedNode</code></a> can be |
| used to provide comments associated with an arbitrary |
| <a href="/pkg/go/ast/#Node"><code>ast.Node</code></a> (until now only |
| <a href="/pkg/go/ast/#File"><code>ast.File</code></a> carried comment information). |
| </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>The <code>Exec</code> function has been removed; callers should use |
| <code>Exec</code> from the <code>syscall</code> package, where available.</p> |
| |
| <p>The <code>ShellExpand</code> function has been renamed to <a |
| href="/pkg/os/#ExpandEnv"><code>ExpandEnv</code></a>.</p> |
| |
| <p>The <a href="/pkg/os/#NewFile"><code>NewFile</code></a> function |
| now takes a <code>uintptr</code> fd, instead of an <code>int</code>. |
| The <a href="/pkg/os/#File.Fd"><code>Fd</code></a> method on files now |
| also returns a <code>uintptr</code>.</p> |
| |
| <p><em>Updating</em>: 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() |
| Sys() interface{} // underlying data source (can return nil) |
| } |
| </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 has a <code>Sys</code> method that returns 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) |
| } |
| // Check that it's a Unix file. |
| unixStat, ok := fi.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.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="testing_script">The testing/script package</h3> |
| |
| <p> |
| The testing/script package has been deleted. It was a dreg. |
| </p> |
| |
| <p> |
| <em>Updating</em>: |
| No code is likely to be affected. |
| </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> |
| |