Options

The attributes that shape the options Parser.add_options declares from a struct’s fields.

Source: runtime/cli/options.pep

Option

[Attribute] struct Option

Sets how a field of an options struct is declared as an option: its short name, its help, and whether it is required or global. A field without it is still an option, named after the field.

Example

import cli;

struct Options {
    [cli.Option("o", "the executable to write")]
    var output: String = "a.out";
    [cli.Option("v", "say what is happening")]
    var verbose: bool;
}

Fields

short_name

const short_name: String = ""

The one-letter short name, without -, or empty for none.

help

const help: String = ""

What the option does, for the help.

name

const name: String = ""

The long name, without --; empty for the field’s name with each _ written - (import_path is --import-path).

value_name

const value_name: String = ""

What the help calls the value; empty for the long name in capitals.

required

const required: bool = false

Whether leaving the option out is an error.

global

const global: bool = false

Whether the option may also be given after the name of a command, at any depth.

Positional

[Attribute] struct Positional

Declares a field of an options struct as the next positional argument instead of an option. A T field takes one value, required unless the field starts with a value (its default; an empty String or a null io.Path is none); a T? field takes an optional one; a T[] field takes every value that is left.

Example

import cli;

struct Options {
    [cli.Positional("the program's entry file")]
    var source: String;
}

Fields

help

const help: String = ""

What the argument is, for the help.

name

const name: String = ""

What the help and errors call it; empty for the field’s name.

required

const required: bool = false

Whether leaving it out is an error, even when the field has a default; for a T[] field, whether at least one value must be given. A T? field ignores it.