Subcommands

Full subcommand chaining support was added on version 0.3.0.

Say we want a goodbye subcommand for our hello command that prints a farewell message. We can achieve this flawlessly by adding a new subcommand to our hello command.

First, make the handler for it, we’ll need it later:

#![allow(unused)]
fn main() {
// use vecli::*;

fn goodbye(_ctx: &CommandContext) {
    println!("Hello!");
    println!("Goodbye!");
}
}

To add this as a subcommand for our hello command, we can do it like so by using the .subcommand() method:

#![allow(unused)]
fn main() {
// let hello_command = Command::new(...)
// ...

hello_command.subcommand(
    Command::new("goodbye", goodbye)
);
}

Now, when the user runs my-app hello goodbye (or cargo run hello goodbye), the goodbye subcommand will be executed and print a farewell message!

$ my-app hello goodbye
Hello!
Goodbye!

Since subcommands are just regular commands, they can have their own flags, and even subcommands of their own. Configuring them is the same as configuring any other command.

Extra

If you want a command that does nothing and is only a container for subcommands, you can use a separate Command constructor using Command::parent("name"). This is useful for organizing related subcommands together. Running a parent command without a subcommand will print an error by default, so it’s best to pass .print_help_if_no_args(true) to make it print the help message instead.

#![allow(unused)]
fn main() {
let parent_command = Command::parent("parent").print_help_if_no_args(true);
}

Next up, let’s implement the silent flag for our hello command. We can accomplish this by adding Flags