For a full explanation of the motivation and design of Go 1, see XXX. Here follows a summary.
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.
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
go 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.
The original syntax for deleting an element in a map was:
m[x] = ignored, false
In Go 1, that syntax has gone; instead there is a new built-in
function, delete. The call
delete(m, k)
will delete the map entry retrieved by the expression m[k].
There is no return value. Deleting a non-existent entry is a no-op.
Updating:
Gofix will convert expressions of the form m[k] = ignored,
false into delete(m, k) when it is clear that
the ignored value can be safely discarded from the program and
false refers to the predefined boolean constant. Gofix
will flag other uses of the syntax for inspection by the programmer.
Go 1 has a rearranged package hierarchy that groups related items
into subdirectories. For instance, utf8 and
utf16 now occupy subdirectories of unicode.
Also, some packages have moved into
subrepositories of
code.google.com/p/go
while others have been deleted outright.
| Old path | New path |
|---|---|
| asn1 | encoding/asn1 |
| csv | encoding/csv |
| gob | encoding/gob |
| json | encoding/json |
| xml | encoding/xml |
| exp/template/html | html/template |
| big | math/big |
| cmath | math/cmplx |
| rand | math/rand |
| http | net/http |
| http/cgi | net/http/cgi |
| http/fcgi | net/http/fcgi |
| http/httptest | net/http/httptest |
| http/pprof | net/http/pprof |
| net/mail | |
| rpc | net/rpc |
| rpc/jsonrpc | net/rpc/jsonrpc |
| smtp | net/smtp |
| url | net/url |
| exec | os/exec |
| scanner | text/scanner |
| tabwriter | text/tabwriter |
| template | text/template |
| template/parse | text/template/parse |
| utf8 | unicode/utf8 |
| utf16 | unicode/utf16 |
Note that the package names for the old cmath and
exp/template/html packages have changed to cmplx
and template.
Updating: Gofix 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. TODO: should warn about deletions. TODO: should also handle packages that move to subrepos.