Go Language Modularization
External
Internal
Overview
A standard organization of the files that are part of a project makes easier to share code with other people who also use the same standard. Go workspaces encourage such a standard.
Overview
Workspaces
The standard workspace layout is:
. ├─ src ├─ pkg └─ bin
This layout is recommended, but not enforced.
A workspace may contain multiple projects.
Define the relationship between workspace and the GOPATH
variable.
Project
Packages
A package is a group of related source files. A package can be imported by other packages. Always, there must be one package called main
, which produces an executable as result of its compilation. Other packages do not produce executables as result of their compilation.
Must the package live in a directory with the same name?
Deplete, merge into this document and delete: Go Concepts - Packages
Declaring Packages
The main Package
The main
package produces an executable as result of its compilation. The main
package must have a function called main()
, which is where the code execution starts. The name of the source code file that declares the main()
function does not matter, as long as the file is among the package's files. The following code, declared in a blue.go
source file, placed in any directory, not necessarily in a main
directory, produces an executable named main
:
package main
import "fmt"
func main() {
fmt.Printf("hello\n")
}
go build ./blue.go
./main
Importing Packages
When a package is imported during compilation, the compiler searches directories specified by the GOROOT
and GOPATH
environment variables.
import Keyword
The import
is a keyword use to access other packages.
Relationship between Source Code Files and Packages
TODO: how do we add source code files to package? Is it a flat space? It is a hierarchy? What kind of names should the files use?
Standard library
Go comes with a set of "built-in" packages, which come with the Go development environment.
The content of the Standard library is available here: https://pkg.go.dev/std
Interesting Standard library packages:
Dependencies
Vendoring
"Vendoring" is the act of making a local copy of a third party package your project depends on. This copy is traditionally placed inside each project and then saved in the project repository.
TODO
Deplete, merge into this document and delete: