The "go get" command can remotely pull or update code packages and their dependent packages with the help of code management tools, and automatically complete compilation and installation. The "go get" command can dynamically obtain the remote code package. Before using the "go get" command, you need to install a code management tool that matches the remote package, such as Git, SVN, HG, etc., and a package name needs to be provided in the parameter.
The operating environment of this tutorial: Windows 7 system, GO version 1.18, Dell G3 computer.
The go get command can remotely pull or update code packages and their dependent packages with the help of code management tools, and automatically complete compilation and installation. The whole process is as easy as installing an app.
This command can dynamically obtain remote code packages. Currently supported are BitBucket, GitHub, Google Code and Launchpad. Before using the go get command, you need to install a code management tool that matches the remote package, such as Git, SVN, HG, etc., and provide a package name in the parameter.
This command is actually divided into two steps internally: the first step is to download the source code package, and the second step is to execute go install.
go get command - get the code, compile and install with one click
hc@ubt:~$ go get github.com/hyper-carrot/go_lib/logging
Copy after login
Command go getcan be requested upon request And the actual situation is to download or update the specified code package and its dependent packages from the Internet, compile and install them. In the above example, we downloaded a project (or code package) from the famous code hosting site Github and installed it into the first workspace included in the environment variable GOPATH. At the same time, we also know that the import path of this code package is github.com/hyper-carrot/go_lib/logging.
Generally, in order to separate our own and third-party code, we will set up two or more workspaces. We now have a workspace with the directory path /home/hc/golang/lib, and it is the first directory path in the environment variable GOPATH value. Note that the path contained in the environment variable GOPATH cannot be the same as the value of the environment variable GOROOT. Well, if we use the go get command to download and install code packages, then these code packages will be installed in the workspace above. Let's temporarily call this workspace the Lib workspace. After we run go get github.com/hyper-carrot/go_lib/logging, the code package should be saved in the src directory of the Lib work and has been properly installed, as shown below:
On the other hand, if we want to upload a project to the Github website (or other code hosting website) and be used by others, then we should treat the project as a code package. In fact, we have mentioned the reason before. The go get command will store all subdirectories and source code files under the project into the src directory of the first workspace, and all subdirectories under the src directory They will all be part or all of the import path of a certain code package. In other words, we should store subcode packages and source code files directly in the project directory, and the package name declared by the source code file directly stored in the project directory should be the same as the project name (unless it is a command source code file). Doing this will allow others to use your project directly after downloading it from the Github site using the go get command.
In fact, it is not recommended to directly use the path of the project root directory as the workspace path like the goc2p project. The main reason for doing this is to make it easier for readers to understand the project structure and workspace concepts of the Go language, and also to allow readers to see another project structure. Of course, if your project uses tools like gb, that is another matter. The root directory of such a project should be considered a workspace (but you do not need to add it to the GOPATH environment variable). It should be downloaded somewhere outside the Go language workspace by git clone instead of using the go get command.
Remote import path analysis
In fact, the action performed by the go get command is also called code package remote import, and is passed to the The parameter of the command that is the code package import path is also called the code package remote import path. The
go get command can not only download code packages from famous code hosting sites like Github, but also from any code version control system (English Version Control System, referred to as Check out the code package for VCS). Any code hosting site provides code upload and download services through one or more code version control systems. So, more strictly speaking, what the go get command does is check out/update the code package from the remote repository of the code version control system and compile and install it.
The VCS information supported by this command is as follows:
Table 0-2 go getVCS supported by the command
Name
Main command
Description
##Mercurial
hg
Mercurial is a lightweight distributed version control system, implemented in Python language, easy to learn and use, and highly scalable.
Git
git
Git was originally an open source distributed version control software developed by Linux Torvalds to help manage Linux kernel development. But it is now widely used. It is used for effective, high-speed version management of projects of all sizes.
Subversion
svn
Subversion is a version control system and the first system to incorporate the concept and functionality of branches into the version control model. But compared to Git and Mercurial, it is only a member of the traditional version control system.
Bazaar
bzr
Bazaar is an open source distributed version control system. But in comparison, there are not many projects that use it as a VCS.
The go get command must know the version control system and the URL of the remote warehouse corresponding to the remote import path of the code package before checking out the code package.
If the code package already exists in the local workspace, these pieces of information will be determined directly by analyzing its path. Several version control systems supported by the
go get command have one thing in common, that is, a metadata directory will be stored in the checked-out project directory, with a name prefixed with "." plus its main command name. For example, Git will add a subdirectory named ".git" to the checked-out project directory. Therefore, it is easy to determine the version control system used by the code package. In addition, since the code package already exists, we only need to update the code package through the update command of the code version control system, so there is no need to know the URL of its remote warehouse. For code packages that already exist in the local workspace, the go get command will not perform repeated downloads unless the code package is forcibly updated. If you want to forcibly update the code package, you can add the -u tag when executing the go get command. This markup will be introduced later.
If the code package does not exist in the local workspace, the relevant information can only be obtained by analyzing the remote import path of the code package. First, the
go get command will perform static analysis on the remote import path of the code package. In order to make the analysis process more convenient and faster, the go get command program has preset the information of several famous code hosting websites. As shown in the following table:
Table 0-3 Information about the preset code hosting site
代码包analyzer实际上属于我的一个网络爬虫项目。这个项目的代码被托管在了Github网站上。它的网址是：https://github.com/hyper-carrot/talon。如果用标准的导入路径来下载analyzer代码包的话，命令应该这样写go get github.com/hyper-carrot/talon/analyzer。不过，如果我们像上面的示例那样在该代码包中的一个源码文件中加入导入注释的话，这样下载它就行不通了。我们来看一看这个导入注释。
hc@ubt:~$ go get github.com/hyper-carrot/talon/analyzer
package github.com/hyper-carrot/talon/analyzer: code in directory /home/hc/golang/lib/src/github.com/hyper-carrot/talon/analyzer expects import "hypermind.cn/talon/analyzer"
hc@ubt:~$ cd ~/golang/lib/src/github.com/hyper-carrot/go_lib
hc@ubt:~/golang/lib/src/github.com/hyper-carrot/go_lib$ git tag go1
hc@ubt:~$ go get -v -u -x github.com/hyper-carrot/go_lib
github.com/hyper-carrot/go_lib (download)
cd /home/hc/golang/lib/src/github.com/hyper-carrot/go_lib
git fetch
cd /home/hc/golang/lib/src/github.com/hyper-carrot/go_lib
git show-ref
cd /home/hc/golang/lib/src/github.com/hyper-carrot/go_lib
git show-ref tags/go1 origin/go1
cd /home/hc/golang/lib/src/github.com/hyper-carrot/go_lib
git checkout tags/go1
WORK=/tmp/go-build636338114
Commandgo getThis function is very useful. When our code directly or indirectly depends on some code packages that are developed for multiple Go language versions at the same time, the correct version can be automatically checked out. It can also be said that the go get command has built-in functions for multi-version dependency management of code packages.
Here, I introduce to you how to use the go get command. The go get command, like the two commands introduced before, is an indispensable auxiliary tool when we write Go language programs and build Go language projects.
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