CLAP aims at being powerful and advanced command line interface library for the Python 3 language. Having built-in support for modes, optional and obligatory options, options with arguments (with type-checking with arbitrary types) it enables programmers to create rich command line interfaces for Python 3 programs.

• support for single-level and nested modes (with per-mode and global options),
• support for grouped short options (ls -lhR),
• support for long options with or without equal-sign-connected arguments (--log=./file.log and --log ./file.log are both correct),
• support for option aliases (short/long names),
• support for typed arguments (str, int, float built-in and other arbitrary types via callbacks),
• built-in type checking of option arguments,
• support for multiple arguments for options (e.g. --point 0 0),
• checking for missing arguments with options which require them,
• checking for conflicting options (eg. --quiet must not come with option --verbose),
• support for options that MUST be passed to the program,
• support for options required by other options (e.g. --key requires --value),
• support for options wanted by other options (e.g. --which wants --this or --that or both),
• good set of exceptions with detailed error messages,
• ability to load interface from JSON descriptions,
• automatic generation of help screens (for your-tool help command) with per-mode, per-option, and per-operand descriptions, usage examples, and more
• support for shortcuts for command names (shortest-unique name is sufficient for CLAP to resolve the command, it is not necessary to write full names)

CLAP is not the most easy to use command line arguments parser for Python, but I am quite confident that it is one of the most powerful (if not the most powerful) framework for writing command line interfaces. With excellent support for modes, options, and operands, automatic input verification, and help screen generation you get a big return on your investment.

See the Issue project which is the flagship software for CLAP and uses all features the library offers.

RedCLAP is published under GNU GPL v3 or GNU LGPL v3 (or any later version of one of this licenses).