Lexopt

Lexopt is an argument parser for Rust. It tries to have the simplest possible design that's still correct. It's so simple that it's a bit tedious to use.

Lexopt is:

• Small: one file, no dependencies, no macros. Easy to audit.
• Correct: standard conventions are supported and ambiguity is avoided.
• Imperative: options are returned as they are found, nothing is declared ahead of time.
• Minimalist: only basic functionality is provided.
• Unhelpful: there is no help generation and error messages often lack context.

Examples

For basic usage, see examples/cargo.rs. For more details, see src/tests.rs.

Command line syntax

The following conventions are supported:

• Short options (-q)
• Long options (--verbose)
• -- to mark the end of options
• = to separate options from values (--option=value, -o=value)
  • The nonstandard -o=value syntax can be disabled by Parser::set_short_equals().
• Spaces to separate options from values (--option value, -o value)
• Unseparated short options (-ovalue)
• Combined short options (-abc to mean -a -b -c)
• Options with optional arguments (like GNU sed's -i, which can be used standalone or as -iSUFFIX) (Parser::optional_value())

These are not supported out of the box:

• Single-dash long options (like find's -name)
• Abbreviated long options (GNU's getopt lets you write --num instead of --number if it can be expanded unambiguously)

Why not?

This library may not be worth using if:

• You don't care about code size
• You do care about great error messages
• You hate boilerplate

See also

• rustc's getopts.
• clap.