new option type "file"

[alexkli]

Many CLI options are meant to be paths to files. Instead of having to use string as type today, and doing the basic file handling in your app, it would be nice to have a dedicated file type for options in yargs.

If an option is of type file yargs would:

• check if the file exists and if not throw an error with a standard message
• run it through path.resolve() and return that as option value to the app
• make bash autocompletion support expect a file here so that -f <TAB> will present available files

This new option would mean these API additions:

• file(key)
• option[s](key, opt) would take a new opt.file boolean, as well as support 'file' as value for opt.type

[honzajavorek]

FWIW, in Python's click there are two types to handle this: file and path

[alexkli]

BTW, for now I am using coerce to resolve a path argument like in this example:

yargs.positional('file', {
    type: 'string',
    describe: 'Path to input file',
    coerce: f => path.resolve(f)
})