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Lesson 26Using Modules

Modules are important because they allow you to organize related code files into the same package and organize the code in a way that promotes simplicity and reusability. In this lesson, you'll learn the steps needed to set up and use modules.

LEARNING OBJECTIVES

By the end of this lesson, you will be able to:

• Create a Go module containing your own functions.
• Test the functions in your Go module.
• Call the functions in your Go module from other programs.

GETTING STARTED WITH MODULES

From a code perspective, a module is a collection of Go packages and files along with a file called go.mod. In the following steps, you'll learn how to create a module and then use it.

STEP 1: CREATE THE PROJECT DIRECTORY

First, create a directory with the same name that will be used for your module. In our example, you use the module and directory name mymodule. Create this directory under $GOPATH/src. On our system, this is /opt/homebrew/Cellar/go/1.17.6/libexec/src/mymodule. You can create a directory on Linux by entering the following commands on the command line:

user src % mkdir mymodule
user src % cd mymodule
user mymodule % ls
user mymodule % 

On a Windows system, in a command window, you can create the new mymodule directory as follows:

C:\User\YourName\go\src> md mymodule
C:\User\YourName\go\src> cd mymodule
C:\User\YourName\go\src> dir
Directory of C:\Users\YourName\go\src\mymodule
 
04/20/2022  11:22 AM    <DIR>          .
04/20/2022  11:22 AM    <DIR>          ..

STEP 2: ...