mirror of
https://github.com/golang/go
synced 2024-11-13 17:40:23 -07:00
doc: simplify How to write Go code article
This version just tells you what to do, rather than trying to teach you how it all works. Should be much better for newcomers. R=dave, gary.burd, alcosholik, r CC=golang-dev https://golang.org/cl/8247044
This commit is contained in:
Andrew Gerrand
parent
57af97f2f4
commit
ee923e3f90
675
doc/code.html
675
doc/code.html
@ -6,143 +6,407 @@
|
||||
|
||||
<p>
|
||||
This document demonstrates the development of a simple Go package and
|
||||
introduces the <a href="/cmd/go/">go command</a>, the standard way to fetch,
|
||||
introduces the <a href="/cmd/go/">go tool</a>, the standard way to fetch,
|
||||
build, and install Go packages and commands.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
This content is also available as a <a href="http://www.youtube.com/watch?v=XCsL89YtqCs">screencast</a>.
|
||||
The <code>go</code> tool requires you to organize your code in a specific
|
||||
way. Please read this document carefully.
|
||||
It explains the simplest way to get up and running with your Go installation.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
A similar explanation is available as a
|
||||
<a href="http://www.youtube.com/watch?v=XCsL89YtqCs">screencast</a>.
|
||||
</p>
|
||||
|
||||
|
||||
<h2 id="GOPATH">Code organization</h2>
|
||||
|
||||
<h3><code>GOPATH</code> and workspaces</h3>
|
||||
<h3 id="Workspaces">Workspaces</h3>
|
||||
|
||||
<p>
|
||||
One of Go's design goals is to make writing software easier. To that end, the
|
||||
<code>go</code> command doesn't use Makefiles or other configuration files to
|
||||
guide program construction. Instead, it uses the source code to find
|
||||
dependencies and determine build conditions. This means your source code and
|
||||
build scripts are always in sync; they are one and the same.
|
||||
The <code>go</code> tool is designed to work with open source code maintained
|
||||
in public repositories. Although you don't need to publish your code, the model
|
||||
for how the environment is set up works the same whether you do or not.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
The one thing you must do is set a <code>GOPATH</code> environment variable.
|
||||
<code>GOPATH</code> tells the <code>go</code> command (and other related tools)
|
||||
where to find and install the Go packages on your system.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
<code>GOPATH</code> is a list of paths. It shares the syntax of your system's
|
||||
<code>PATH</code> environment variable. A typical <code>GOPATH</code> on
|
||||
a Unix system might look like this:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
GOPATH=/home/user/ext:/home/user/mygo
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
(On a Windows system use semicolons as the path separator instead of colons.)
|
||||
</p>
|
||||
|
||||
<p>
|
||||
Each path in the list (in this case <code>/home/user/ext</code> or
|
||||
<code>/home/user/mygo</code>) specifies the location of a <i>workspace</i>.
|
||||
A workspace contains Go source files and their associated package objects, and
|
||||
command executables. It has a prescribed structure of three subdirectories:
|
||||
Go code must be kept inside a <i>workspace</i>.
|
||||
A workspace is a directory hierarchy with three directories at its root:
|
||||
</p>
|
||||
|
||||
<ul>
|
||||
<li><code>src</code> contains Go source files,
|
||||
<li><code>pkg</code> contains compiled package objects, and
|
||||
<li><code>src</code> contains Go source files organized into packages (one package per directory),
|
||||
<li><code>pkg</code> contains package objects, and
|
||||
<li><code>bin</code> contains executable commands.
|
||||
</ul>
|
||||
|
||||
<p>
|
||||
Subdirectories of the <code>src</code> directory hold independent packages, and
|
||||
all source files (<code>.go</code>, <code>.c</code>, <code>.h</code>, and
|
||||
<code>.s</code>) in each subdirectory are elements of that subdirectory's
|
||||
package.
|
||||
The <code>go</code> tool builds source packages and installs the resulting
|
||||
binaries to the <code>pkg</code> and <code>bin</code> directories.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
When building a program that imports the package "<code>widget</code>" the
|
||||
<code>go</code> command looks for <code>src/pkg/widget</code> inside the Go root,
|
||||
and then—if the package source isn't found there—it searches
|
||||
for <code>src/widget</code> inside each workspace in order.
|
||||
The <code>src</code> subdirectory typically contains multiple version control
|
||||
repositories (such as for Git or Mercurial) that track the development of one
|
||||
or more source packages.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
Multiple workspaces can offer some flexibility and convenience, but for now
|
||||
we'll concern ourselves with only a single workspace.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
Let's work through a simple example. First, create a <code>$HOME/mygo</code>
|
||||
directory and its <code>src</code> subdirectory:
|
||||
To give you an idea of how a workspace looks in practice, here's an example:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ mkdir -p $HOME/mygo/src # create a place to put source code
|
||||
bin/
|
||||
streak # command executable
|
||||
todo # command executable
|
||||
pkg/
|
||||
linux_amd64/
|
||||
code.google.com/p/goauth2/
|
||||
oauth.a # package object
|
||||
github.com/nf/todo/
|
||||
task.a # package object
|
||||
src/
|
||||
code.google.com/p/goauth2/
|
||||
.hg/ # mercurial repository metadata
|
||||
oauth/
|
||||
oauth.go # package source
|
||||
oauth_test.go # test source
|
||||
github.com/nf/
|
||||
streak/
|
||||
.git/ # git repository metadata
|
||||
oauth.go # command source
|
||||
streak.go # command source
|
||||
todo/
|
||||
.git/ # git repository metadata
|
||||
task/
|
||||
task.go # package source
|
||||
todo.go # command source
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
Next, set it as the <code>GOPATH</code>. You should also add the
|
||||
<code>bin</code> subdirectory to your <code>PATH</code> environment variable so
|
||||
that you can run the commands therein without specifying their full path.
|
||||
To do this, add the following lines to <code>$HOME/.profile</code> (or
|
||||
equivalent):
|
||||
This workspace contains three repositories (<code>goauth2</code>,
|
||||
<code>streak</code>, and <code>todo</code>) comprising two commands
|
||||
(<code>streak</code> and <code>todo</code>) and two libraries
|
||||
(<code>oauth</code> and <code>task</code>).
|
||||
</p>
|
||||
|
||||
<p>
|
||||
Commands and libraries are built from different kinds of source packages.
|
||||
We will discuss the distinction <a href="#PackageNames">later</a>.
|
||||
</p>
|
||||
|
||||
|
||||
<h3 id="GOPATH">The <code>GOPATH</code> environment variable</h3>
|
||||
|
||||
<p>
|
||||
The <code>GOPATH</code> environment variable specifies the location of your
|
||||
workspace. It is likely the only environment variable you'll need to set
|
||||
when developing Go code.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
To get started, create a workspace directory and set <code>GOPATH</code>
|
||||
accordingly. Your workspace can be located wherever you like, but we'll use
|
||||
<code>$HOME/go</code> in this document. Note that this must <b>not</b> be the
|
||||
same path as your Go installation.
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
export GOPATH=$HOME/mygo
|
||||
export PATH=$PATH:$HOME/mygo/bin
|
||||
$ <b>mkdir $HOME/go</b>
|
||||
$ <b>export GOPATH=$HOME/go</b>
|
||||
</pre>
|
||||
|
||||
|
||||
<h3>Import paths</h3>
|
||||
|
||||
<p>
|
||||
The standard packages are given short import paths such as <code>"fmt"</code>
|
||||
and <code>"net/http"</code> for convenience.
|
||||
For your own projects, it is important to choose a base import path that is
|
||||
unlikely to collide with future additions to the standard library or other
|
||||
external libraries.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
The best way to choose an import path is to use the location of your version
|
||||
control repository.
|
||||
For instance, if your source repository is at <code>example.com</code>
|
||||
or <code>code.google.com/p/example</code>, you should begin your package
|
||||
paths with that URL, as in "<code>example.com/foo/bar</code>" or
|
||||
"<code>code.google.com/p/example/foo/bar</code>".
|
||||
Using this convention, the <code>go</code> command can automatically check out and
|
||||
build the source code by its import path alone.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
If you don't intend to install your code in this way, you should at
|
||||
least use a unique prefix like "<code>widgets/</code>", as in
|
||||
"<code>widgets/foo/bar</code>". A good rule is to use a prefix such as your
|
||||
company or project name, since it is unlikely to be used by another group.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
We'll use <code>example/</code> as our base import path:
|
||||
For convenience, add the workspace's <code>bin</code> subdirectory
|
||||
to your <code>PATH</code>:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ mkdir -p $GOPATH/src/example
|
||||
$ <b>export PATH=$PATH:$HOME/go/bin</b>
|
||||
</pre>
|
||||
|
||||
|
||||
<h3>Package names</h3>
|
||||
<h3 id="PackagePaths">Package paths</h3>
|
||||
|
||||
<p>
|
||||
The first statement in a Go source file should be
|
||||
The packages from the standard library are given short paths such as
|
||||
<code>"fmt"</code> and <code>"net/http"</code>.
|
||||
For your own packages, you must choose a base path that is unlikely to
|
||||
collide with future additions to the standard library or other external
|
||||
libraries.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
If you keep your code in a source repository somewhere, then you should use the
|
||||
root of that source repository as your base path.
|
||||
For instance, if you have a <a href="https://github.com/">GitHub</a> account at
|
||||
<code>github.com/user</code>, that should be your base path.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
Note that you don't need to publish your code to a remote repository before you
|
||||
can build it. It's just a good habit to organize your code as if you will
|
||||
publish it someday. In practice you can choose any arbitrary path name,
|
||||
as long as it is unique to the standard library and greater Go ecosystem.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
We'll use <code>github.com/user</code> as our base path. Create a directory
|
||||
inside your workspace in which to keep source code:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ <b>mkdir -p $GOPATH/src/github.com/user</b>
|
||||
</pre>
|
||||
|
||||
|
||||
<h3 id="Command">Your first program</h3>
|
||||
|
||||
<p>
|
||||
To compile and run a simple program, first choose a package path (we'll use
|
||||
<code>github.com/user/hello</code>) and create a corresponding package directory
|
||||
inside your workspace:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ <b>mkdir $GOPATH/src/github.com/user/hello</b>
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
Next, create a file named <code>hello.go</code> inside that directory,
|
||||
containing the following Go code.
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
package main
|
||||
|
||||
import "fmt"
|
||||
|
||||
func main() {
|
||||
fmt.Printf("Hello, world.\n")
|
||||
}
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
Now you can build and install that program with the <code>go</code> tool:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ <b>go install github.com/user/hello</b>
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
Note that you can run this command from anywhere on your system. The
|
||||
<code>go</code> tool finds the source code by looking for the
|
||||
<code>github.com/user/hello</code> package inside the workspace specified by
|
||||
<code>GOPATH</code>.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
You can also omit the package path if you run <code>go install</code> from the
|
||||
package directory:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ <b>cd $GOPATH/src/github.com/user/hello</b>
|
||||
$ <b>go install</b>
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
This command builds the <code>hello</code> command, producing an executable
|
||||
binary. It then installs that binary to the workspace's <code>bin</code>
|
||||
directory as <code>hello</code> (or, under Windows, <code>hello.exe</code>).
|
||||
In our example, tha will be <code>$GOPATH/bin/hello</code>, which is
|
||||
<code>$HOME/go/bin/hello</code>.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
The <code>go</code> tool will only print output when an error occurs, so if
|
||||
these commands produce no output they have executed successfully.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
You can now run the program by typing its full path at the command line:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ <b>$GOPATH/bin/hello</b>
|
||||
Hello!
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
Or, as you have added <code>$GOPATH/bin</code> to your <code>PATH</code>,
|
||||
just type the binary name:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ <b>hello</b>
|
||||
Hello!
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
If you're using a source control system, now would be a good time to initialize
|
||||
a repository, add the files, and commit your first change. Again, this step is
|
||||
optional: you do not need to use source control to write Go code.
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ <b>cd $GOPATH/src/github.com/user/hello</b>
|
||||
$ <b>git init</b>
|
||||
Initialized empty Git repository in /home/user/go/src/github.com/user/hello/.git/
|
||||
$ <b>git add hello.go</b>
|
||||
$ <b>git commit -m "initial commit"</b>
|
||||
[master (root-commit) 0b4507d] initial commit
|
||||
1 file changed, 1 insertion(+)
|
||||
create mode 100644 hello.go
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
Pushing the code to a remote repository is left as an exercise for the reader.
|
||||
</p>
|
||||
|
||||
|
||||
<h3 id="Library">Your first library</h3>
|
||||
|
||||
<p>
|
||||
Let's write a library and use it from the <code>hello</code> program.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
Again, the first step is to choose a package path (we'll use
|
||||
<code>github.com/user/newmath</code>) and create the package directory:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ <b>mkdir $GOPATH/src/github.com/user/newmath</b>
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
Next, create a file named <code>sqrt.go</code> in that directory with the
|
||||
following contents.
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
// Package newmath is a trivial example package.
|
||||
package newmath
|
||||
|
||||
// Sqrt returns an approximation to the square root of x.
|
||||
func Sqrt(x float64) float64 {
|
||||
z := 0.0
|
||||
for i := 0; i < 1000; i++ {
|
||||
z -= (z*z - x) / (2 * x)
|
||||
}
|
||||
return z
|
||||
}
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
Now, test that the package compiles with <code>go build</code>:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ <b>go build github.com/user/newmath</b>
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
Or, if you are working in the package's source directory, just:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ <b>go build</b>
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
This won't produce an output file. To do that, you must use <code>go
|
||||
install</code>, which places the package object inside the <code>pkg</code>
|
||||
directory of the workspace.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
After confirming that the <code>newmath</code> package builds,
|
||||
modify your original <code>hello.go</code> (which is in
|
||||
<code>$GOPATH/src/github.com/user/hello</code>) to use it:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
package main
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
|
||||
<b>"github.com/user/newmath"</b>
|
||||
)
|
||||
|
||||
func main() {
|
||||
fmt.Printf("Hello, world. <b>Sqrt(2) = %v\n", newmath.Sqrt(2)</b>)
|
||||
}
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
Whenever the <code>go</code> tool installs a package or binary, it also
|
||||
installs whatever dependencies it has. So when you install the <code>hello</code>
|
||||
program
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ <b>go install github.com/user/hello</b>
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
the <code>newmath</code> package will be installed as well, automatically.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
Running the new version of the program, you should see some numerical output:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ <b>hello</b>
|
||||
Hello, world. Sqrt(2) = 1.414213562373095
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
After the steps above, your workspace should look like this:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
bin/
|
||||
hello # command executable
|
||||
pkg/
|
||||
linux_amd64/ # this will reflect your OS and architecture
|
||||
github.com/user/
|
||||
newmath.a # package object
|
||||
src/
|
||||
github.com/user/
|
||||
hello/
|
||||
hello.go # command source
|
||||
newmath/
|
||||
sqrt.go # package source
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
Note that <code>go install</code> placed the <code>newmath.a</code> object in a
|
||||
directory inside <code>pkg/linux_amd64</code> that mirrors its source
|
||||
directory.
|
||||
This is so that future invocations of the <code>go</code> tool can find the
|
||||
package object and avoid recompiling the package unnecessarily.
|
||||
The <code>linux_amd64</code> part is there to aid in cross-compilation,
|
||||
and will reflect the operating system and architecture of your system.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
Go command exectuables are statically linked; the package objects need not
|
||||
be present to run Go programs.
|
||||
</p>
|
||||
|
||||
|
||||
<h3 id="PackageNames">Package names</h3>
|
||||
|
||||
<p>
|
||||
The first statement in a Go source file must be
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
@ -158,209 +422,24 @@ where <code><i>name</i></code> is the package's default name for imports.
|
||||
Go's convention is that the package name is the last element of the
|
||||
import path: the package imported as "<code>crypto/rot13</code>"
|
||||
should be named <code>rot13</code>.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
Executable commands must always use <code>package main</code>.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
There is no requirement that package names be unique
|
||||
across all packages linked into a single binary,
|
||||
only that the import paths (their full file names) be unique.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
Create a new package under <code>example</code> called <code>newmath</code>:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ cd $GOPATH/src/example
|
||||
$ mkdir newmath
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
Then create a file named <code>$GOPATH/src/example/newmath/sqrt.go</code>
|
||||
containing the following Go code:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
// Package newmath is a trivial example package.
|
||||
package newmath
|
||||
|
||||
// Sqrt returns an approximation to the square root of x.
|
||||
func Sqrt(x float64) float64 {
|
||||
// This is a terrible implementation.
|
||||
// Real code should import "math" and use math.Sqrt.
|
||||
z := 0.0
|
||||
for i := 0; i < 1000; i++ {
|
||||
z -= (z*z - x) / (2 * x)
|
||||
}
|
||||
return z
|
||||
}
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
This package is imported by the path name of the directory it's in, starting
|
||||
after the <code>src</code> component:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
import "example/newmath"
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
See <a href="/doc/effective_go.html#names">Effective Go</a> to learn more about
|
||||
Go's naming conventions.
|
||||
</p>
|
||||
|
||||
|
||||
<h2>Building and installing</h2>
|
||||
|
||||
<p>
|
||||
The <code>go</code> command comprises several subcommands, the most central being
|
||||
<code>install</code>. Running <code>go install <i>importpath</i></code> builds
|
||||
and installs a package and its dependencies.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
To "install a package" means to write the package object or executable command
|
||||
to the <code>pkg</code> or <code>bin</code> subdirectory of the workspace in
|
||||
which the source resides.
|
||||
</p>
|
||||
|
||||
<h3>Building a package</h3>
|
||||
|
||||
<p>
|
||||
To build and install the <code>newmath</code> package, type
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ go install example/newmath
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
This command will produce no output if the package and its dependencies
|
||||
are built and installed correctly.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
As a convenience, the <code>go</code> command will assume the current directory
|
||||
if no import path is specified on the command line. This sequence of commands
|
||||
has the same effect as the one above:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ cd $GOPATH/src/example/newmath
|
||||
$ go install
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
The resulting workspace directory tree (assuming we're running Linux on a 64-bit
|
||||
system) looks like this:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
pkg/
|
||||
linux_amd64/
|
||||
example/
|
||||
newmath.a # package object
|
||||
src/
|
||||
example/
|
||||
newmath/
|
||||
sqrt.go # package source
|
||||
</pre>
|
||||
|
||||
|
||||
<h3>Building a command</h3>
|
||||
|
||||
<p>
|
||||
The <code>go</code> command treats code belonging to <code>package main</code> as
|
||||
an executable command and installs the package binary to the
|
||||
<code>GOPATH</code>'s <code>bin</code> subdirectory.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
Add a command named <code>hello</code> to the source tree.
|
||||
First create the <code>example/hello</code> directory:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ cd $GOPATH/src/example
|
||||
$ mkdir hello
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
Then create the file <code>$GOPATH/src/example/hello/hello.go</code>
|
||||
containing the following Go code.
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
// Hello is a trivial example of a main package.
|
||||
package main
|
||||
|
||||
import (
|
||||
"example/newmath"
|
||||
"fmt"
|
||||
)
|
||||
|
||||
func main() {
|
||||
fmt.Printf("Hello, world. Sqrt(2) = %v\n", newmath.Sqrt(2))
|
||||
}
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
Next, run <code>go install</code>, which builds and installs the binary to
|
||||
<code>$GOPATH/bin</code> (or <code>$GOBIN</code>, if set; to simplify
|
||||
presentation, this document assumes <code>GOBIN</code> is unset):
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ go install example/hello
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
To run the program, invoke it by name as you would any other command:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ $GOPATH/bin/hello
|
||||
Hello, world. Sqrt(2) = 1.414213562373095
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
If you added <code>$HOME/mygo/bin</code> to your <code>PATH</code>, you may omit
|
||||
the path to the executable:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ hello
|
||||
Hello, world. Sqrt(2) = 1.414213562373095
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
The workspace directory tree now looks like this:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
bin/
|
||||
hello # command executable
|
||||
pkg/
|
||||
linux_amd64/
|
||||
example/
|
||||
newmath.a # package object
|
||||
src/
|
||||
example/
|
||||
hello/
|
||||
hello.go # command source
|
||||
newmath/
|
||||
sqrt.go # package source
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
The <code>go</code> command also provides a <code>build</code> command, which is
|
||||
like <code>install</code> except it builds all objects in a temporary directory
|
||||
and does not install them under <code>pkg</code> or <code>bin</code>.
|
||||
When building a command an executable named after the last element of the
|
||||
import path is written to the current directory. When building a package,
|
||||
<code>go build</code> serves merely to test that the package and its
|
||||
dependencies can be built. (The resulting package object is thrown away.)
|
||||
</p>
|
||||
|
||||
|
||||
<h2 id="Testing">Testing</h2>
|
||||
|
||||
<p>
|
||||
@ -379,8 +458,8 @@ if the function calls a failure function such as <code>t.Error</code> or
|
||||
|
||||
<p>
|
||||
Add a test to the <code>newmath</code> package by creating the file
|
||||
<code>$GOPATH/src/example/newmath/sqrt_test.go</code> containing the following
|
||||
Go code.
|
||||
<code>$GOPATH/src/github.com/user/newmath/sqrt_test.go</code> containing the
|
||||
following Go code.
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
@ -397,12 +476,22 @@ func TestSqrt(t *testing.T) {
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
Now run the test with <code>go test</code>:
|
||||
Then run the test with <code>go test</code>:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ go test example/newmath
|
||||
ok example/newmath 0.165s
|
||||
$ <b>go test github.com/user/newmath</b>
|
||||
ok github.com/user/newmath 0.165s
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
As always, if you are running the <code>go</code> tool from the package
|
||||
directory, you can omit the package path:
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ <b>go test</b>
|
||||
ok github.com/user/newmath 0.165s
|
||||
</pre>
|
||||
|
||||
<p>
|
||||
@ -415,7 +504,7 @@ Run <code><a href="/cmd/go/#hdr-Test_packages">go help test</a></code> and see t
|
||||
|
||||
<p>
|
||||
An import path can describe how to obtain the package source code using a
|
||||
revision control system such as Git or Mercurial. The <code>go</code> command uses
|
||||
revision control system such as Git or Mercurial. The <code>go</code> tool uses
|
||||
this property to automatically fetch packages from remote repositories.
|
||||
For instance, the examples described in this document are also kept in a
|
||||
Mercurial repository hosted at Google Code,
|
||||
@ -425,8 +514,8 @@ If you include the repository URL in the package's import path,
|
||||
</p>
|
||||
|
||||
<pre>
|
||||
$ go get code.google.com/p/go.example/hello
|
||||
$ $GOPATH/bin/hello
|
||||
$ <b>go get code.google.com/p/go.example/hello</b>
|
||||
$ <b>$GOPATH/bin/hello</b>
|
||||
Hello, world. Sqrt(2) = 1.414213562373095
|
||||
</pre>
|
||||
|
||||
@ -449,7 +538,7 @@ pkg/
|
||||
linux_amd64/
|
||||
code.google.com/p/go.example/
|
||||
newmath.a # package object
|
||||
example/
|
||||
github.com/user/
|
||||
newmath.a # package object
|
||||
src/
|
||||
code.google.com/p/go.example/
|
||||
@ -458,7 +547,7 @@ src/
|
||||
newmath/
|
||||
sqrt.go # package source
|
||||
sqrt_test.go # test source
|
||||
example/
|
||||
github.com/user/
|
||||
hello/
|
||||
hello.go # command source
|
||||
newmath/
|
||||
@ -485,7 +574,7 @@ has a list of external Go projects including programs and libraries.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
For more information on using remote repositories with the <code>go</code> command, see
|
||||
For more information on using remote repositories with the <code>go</code> tool, see
|
||||
<code><a href="/cmd/go/#hdr-Remote_import_path_syntax">go help remote</a></code>.
|
||||
</p>
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user