Module bpaf::params

Expand description

Primitives to define parsers

A simple no-argument command line option that takes no extra parameters, when decoded produces a fixed value. Can have a short (-f) or a long (--flag) name, see Named::flag and Named::req_flag. bpaf parses flag into a fixed value known at a compile time.

For example --help and -q are long and short flags accepted by cargo

% cargo --help -q

Switch

A special case of a flag that gets decoded into a bool, see Named::switch.

It’s possible to represent flags --help and -q as booleans, true for present and false for absent.

% cargo --help -q

Argument

A command line option with a name that also takes a value. Can have a short (-f value) or a long (--flag value) name, see Named::argument.

For example rustc takes a long argument --explain with a value containing error code:

% rustc --explain E0571

Positional

A positional command with no additonal name, for example in vim main.rs main.rs is a positional argument. See positional.

For example rustc takes input as positional argument:

% rustc hello.rs

Command

A command defines a starting point for an independent subparser. See command.

For example cargo contains a command check that accepts --workspace switch.

% cargo check --workspace

Structs

Named

A named thing used to create Flag, Switch or Argument.

Functions

command

Subcommand parser

env

Environment variable fallback

long

A flag/switch/argument that has a long name

positional

Positional argument that can be encoded as String

positional_if

Positional argument that can be encoded as String and will be taken only if check passes

positional_os

Positional argument in OS specific encoding

short

A flag/switch/argument that has a short name