@cli

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@cli

The @cli module provides a simple interface to easily build CLI applications.

API

cli = require('@cli')

@cli.cmd(name, description, default_flags)

A decorator that registers a command to be executed via CLI:

@cli.cmd("date", "prints the current date", {format: ''})
f date(args, flags) {
    format = flags.format
    return `date ${format}`
}

The name of the command matches the command entered by the user on the CLI (eg. $ ./cli my_command), while the description is used when printing a help message, available through $ ./cli help.

The user can pass however many arguments and flags they want, and they will be passed on to the function defined as command. For example, when the user issues the command $ ./cli a b c --flag 25, args will be ["a", "b", "c", "--flag", "25"] and flags will be {"flag": "25"}. Default flags are there so that, if a flag is not passed, it will be populated with a default value.

@cli.run()

Runs the CLI application:

cli.run()

The application will, by default, have an help command that lists all available commands and is called if no command is provided.

@cli.repl()

Runs the CLI application in interactive mode:

cli.repl()

The application will, by default, have an help command that lists all available commands.

Example CLI app

Here is an example app with 3 commands:

  • the default help
  • date, to print the current date in a specific format
  • ip, to fetch our IP address
#!/usr/bin/env abs
cli = require('@cli')

@cli.cmd("ip", "finds our IP address", {})
f ip_address(arguments, flags) {
    return `curl icanhazip.com`
}

@cli.cmd("date", "Is it Friday already?", {"format": ""})
f date(arguments, flags) {
    format = flags.format
    return `date ${format}`
}

cli.run()

You can save this script as ./cli and make it executable with chmod +x ./cli. Then you will be able to use the CLI app:

$ ./cli 
Available commands:

  * date - Is it Friday already?
  * help - print this help message
  * ip - finds our IP address

$ ./cli help
Available commands:

  * date - Is it Friday already?
  * help - print this help message
  * ip - finds our IP address

$ ./cli ip  
87.201.252.69

$ ./cli date
Sat Apr  4 18:06:35 +04 2020

$ ./cli date --format +%s
1586009212

Example REPL app

Here is an example app with 4 commands:

  • the default help
  • count, which prints a counter
  • incr, which increments a counter by 1
  • incr_by, which increments a counter by a number specified by the user
#!/usr/bin/env abs
cli = require('@cli')

res = {"count": 0}

@cli.cmd("count", "prints a counter", {})
f counter(arguments, flags) {
    echo(res.count)
}

@cli.cmd("incr", "Increment our counter", {})
f incr(arguments, flags) {
    res.count += 1
    return "ok"
}

@cli.cmd("incr_by", "Increment our counter", {})
f incr_by(arguments, flags) {
    echo("Increment by how much?")
    n = stdin().number()
    res.count += n
    return "ok"
}

cli.repl()

You can save this script as ./cli and make it executable with chmod +x ./cli. Then you will be able to use the CLI app:

$ ./cli 
help
Available commands:

  * count - prints a counter
  * help - print this help message
  * incr - Increment our counter
  * incr_by - Increment our counter
count
0
incr
ok
incr
ok
count
2
incr_by
Increment by how much?
-10
ok
count
-8

Next

That’s about it for this section!

You can now head over to read a little bit about the util module.