This is a building series book. It assumes you already know the basics of Go. If not, no worries. You can jump start and learn them quickly from Go's official site at https://golang.org/. Go uses a different way of developing projects. Writing a standalone, simple program doesn't bother you much. But after learning the basics, people try to advance a step further. For that reason, as a Go developer, you should know how Go projects are laid out and the best practices to keep your code clean.
Make sure you have done the following things before proceeding:
- Install Go compiler on your machine
- Set
GOROOTandGOPATHenvironment variables
There are many online references from which you can get to know the preceding details. Depending on your machine type (Windows, Linux, or macOS X), set up a working Go compiler. We see more details about GOPATH in the following section.
GOPATH is nothing but the current appointed workspace on your machine. It is an environment variable that tells the Go compiler about where your source code, binaries, and packages are placed.
The programmers coming from a Python background may know the Virtualenv tool to create multiple projects (with different Python interpreter versions) at the same time. But at a given time, one activates the environment and develops his project. Similarly, you can have any number of Go projects on your machine. While developing, set the GOPATH to one of your projects. The Go compiler now activates that project.
It is a common practice to create a project under the home directory and set the GOPATH environment variable like this:
>mkdir /home/naren/myproject export GOPATH=/home/naren/myproject
Now we install external packages like this:
go get -u -v github.com/gorilla/mux Go copies the project called mux into the currently activated project myproject.
Note
For Go get, use the -u flag to install updated dependencies of the external package and -v to see the verbose details of installation.
A typical Go project has the following structure, as mentioned on the official Go website:
Let us understand this structure before digging further:
bin: Stores the binary of our project; a shippable binary which can be run directlypkg: Contains the package objects; a compiled program which supplies package methodssrc: The place for your project source code, tests, and user packages
In Go, all the packages which you import into your main program have an identical structure, github.com/user/project. But who creates all these directories? Should the developer do that? Nope. It is the developer's responsibility to create directories for his/her project. It means he/she only creates the directory src/github.com/user/hello.
When a developer runs the following command, the directories bin and package are created if they did not exist before. .bin consists of the binary of our project source code and .pkg consists of all internal and external packages we use in our Go programs:
go install github.com/user/project