pico-args

An ultra simple CLI arguments parser.

If you think that this library doesn't support some feature, it's probably intentional.

• No help generation.
• Only flags, options, free arguments and subcommands are supported.
• Options can be separated by a space, = or nothing. See build features.
• Arguments can be in any order.
• Non UTF-8 arguments are supported.

Build features

• eq-separator

  Allows parsing arguments separated by =. Enabled by default.
  This feature adds about 1KiB to the resulting binary.

• short-space-opt

  Makes the space between short keys and their values optional (e.g. -w10).
  If eq-separator is enabled, then it takes precedence and the '=' is not included.
  If eq-separator is disabled, then -K=value gives an error instead of returning "=value".
  The optional space is only applicable for short keys because --keyvalue would be ambiguous.

• combined-flags

  Allows combination of flags, e.g. -abc instead of -a -b -c. If short-space-opt or eq-separator are enabled, you must parse flags after values, to prevent ambiguities.

Alternatives

The core idea of pico-args is to provide some "sugar" for arguments parsing without a lot of overhead (binary or compilation time wise). There are no point in comparing parsing features since pico-args supports only the bare minimum. So we will compare only the size overhead and compilation time.

There are a lot of arguments parsing implementations, but we will use only these one:

• clap - is the most popular and complete one
• gumdrop - a simple parser that uses procedural macros
• structopt - a two above combined
• argh - similar to gumdrop

| | null | pico-args | clap | gumdrop | structopt | argh | |------------------------|---------|-------------|----------|-----------|-------------|---------| | Binary overhead | 0KiB | 14.3KiB | 373.0KiB | 19.8KiB | 371.4KiB | 17.6KiB | | Build time | 0.4s | 0.7s | 5.6s | 4.1s | 6.2s | 4.0s | | Number of dependencies | 0 | 0 | 8 | 5 | 20 | 8 | | Tested version | - | 0.4.0 | 2.33.3 | 0.8.0 | 0.3.21 | 0.1.4 |

• Binary size overhead was measured by subtracting the .text section size of an app with arguments parsing and a hello world app.
• Build time was measured using hyperfine 'cargo clean; cargo build --release'.
• Test projects can be found in test-apps/.

License

MIT