The viper Package: Using Command-Line Flags

Now that we know about working with JSON, XML, and YAML data in Go, we are ready to learn about the viper package.

The flag package

Flags are specially formatted strings that are passed into a program to control its behavior. Dealing with flags on our own might become very frustrating if we want to support multiple flags and options. Go offers the flag package for working with command-line options, parameters, and flags.

The viper package

Although flag can do many things, it is not as capable as other external Go packages. Thus, if we are developing simple UNIX system command-line utilities, we might find the flag package very interesting and useful. Of course, creating simple command-line utilities isn’t the primary learning objective of this course! Therefore, we’ll skip the flag package and introduce an external package named viper, which is a powerful Go package that supports a plethora of options. viper uses the pflag package instead of flag, which is also illustrated in the code we will look at in the following sections. ...