argparse

Command-line argument parser.

Types

ArgumentOption

Configured option handle.

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Parser

Configured parser.

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ParseResult

Values returned by parse.

Fields

• positionals: Dict[String] - Values of configured positional arguments, keyed by positional name.
• options: Dict[Dict[String]] - Present options, keyed by configured long option spelling (including --). Each value dictionary is keyed by its declared value name; a flag has an empty dictionary.

Functions

add_option(parser: Parser, name: String, short_name: String, help: String) -> ArgumentOption

Add an option and return it.

Parameters

1. parser: Parser - Parser to configure.
2. name: String - Long option name, such as --verbose. Foreign parameter.
3. short_name: String - Short option name, such as -v, or an empty string for a long-only option. Foreign parameter.
4. help: String - Help text. Foreign parameter.

Returns

• Configured option handle.

Notes

• An option with no declared values acts as a flag.
• Long names must begin with --. Short names are optional; when provided, they must be - followed by one character. Duplicate option names terminate through std::panic.

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add_option_positional(option: ArgumentOption, name: String, help: String)

Add a positional value consumed by an option.

Parameters

1. option: ArgumentOption - Option returned by add_option.
2. name: String - Value name. Foreign parameter.
3. help: String - Help text. Foreign parameter.

Notes

• Value names must be unique within an option because they become keys in the parse result.

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add_positional(parser: Parser, name: String, help: String)

Add a required positional argument.

Parameters

1. parser: Parser - Parser to configure.
2. name: String - Positional argument name. Foreign parameter.
3. help: String - Help text. Foreign parameter.

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format_help(parser: Parser, r: Region) -> String

Format generated parser help text.

Parameters

1. parser: Parser - Configured parser. Foreign parameter.
2. r: Region - Allocation region for the returned string.

Returns

• Help text.

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new(name: String, r: Region) -> Parser

Create an empty argument parser with a program name for generated help.

Parameters

1. name: String - Program name shown in the usage line. Foreign parameter.
2. r: Region - Allocation region for the parser and all configured data.

Returns

• Parser

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set_description(parser: Parser, description: String)

Set the prose description shown before the generated usage section.

Parameters

1. parser: Parser - Parser to configure.
2. description: String - Description shown before the usage section. Foreign parameter.

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throws parse(parser: Parser, args: Vec[String], r: Region) -> ParseResult

Parse command-line arguments into a result.

Parameters

1. parser: Parser - Configured parser. Foreign parameter.
2. args: Vec[String] - Command-line tokens after the executable name. Foreign parameter.
3. r: Region - Allocation region for the returned result.

Returns

• ParseResult

Notes

• args must not include the executable name. The parsed dictionaries are allocated in r. Options may be written with their long or short names.
• -- ends option parsing. Repeating an option is a parse error.
• Supported forms are --long and -s; grouped short options and inline values such as --output=file are not supported.
• Option values are retrieved by name, such as result.options["--output"]?["file"]?.
• Unknown or repeated options, missing option values, and missing or extra positional arguments return an argparse: error.