Greet multiple is a Higher-order module, which is Terraform's version of a Higher-Order Function. Greet Multiple extends the capability of the Hello World! module by changing the input from a single string to a list of strings.
While you could modify Hello World! to accept both a single string and a list of strings, doing so would cause a significant increase in complexity. Making future changes harder to implement and tests harder to write.
A real-world use case for Higher-order modules would be if you wanted your module to create a resource or allow the resource id to be passed in. Have your "main" module accept the resource id as a variable. Then create a submodule to create the resource and call the "main" module with the resource id that it created.
| Name | Source | Version |
|---|---|---|
| hello | ../../ | n/a |
| Name | Description | Type | Default | Required |
|---|---|---|---|---|
| names | A list of people/things to greet. | list(string) |
n/a | yes |
| Name | Description |
|---|---|
| greeting | A friendly greeting to all of our friends! |