clap/examples/typed-derive.md

This requires enabling the [derive feature flag][crate::_features].

Help:

$ typed-derive --help
Usage: typed-derive[EXE] [OPTIONS]

Options:
  -O <OPTIMIZATION>            Implicitly using `std::str::FromStr`
  -I <DIR>                     Allow invalid UTF-8 paths
      --bind <BIND>            Handle IP addresses
      --sleep <SLEEP>          Allow human-readable durations
  -D <DEFINES>                 Hand-written parser for tuples
      --port <PORT>            Support for discrete numbers [default: 22] [possible values: 22, 80]
      --log-level <LOG_LEVEL>  Support enums from a foreign crate that don't implement `ValueEnum` [default: info] [possible values: info, debug, info, warn, error]
  -h, --help                   Print help

Optimization-level (number)

$ typed-derive -O 1
Args { optimization: Some(1), include: None, bind: None, sleep: None, defines: [], port: 22, log_level: Info }

$ typed-derive -O plaid
? failed
error: invalid value 'plaid' for '-O <OPTIMIZATION>': invalid digit found in string

For more information, try '--help'.

Include (path)

$ typed-derive -I../hello
Args { optimization: None, include: Some("../hello"), bind: None, sleep: None, defines: [], port: 22, log_level: Info }

IP Address

$ typed-derive --bind 192.0.0.1
Args { optimization: None, include: None, bind: Some(192.0.0.1), sleep: None, defines: [], port: 22, log_level: Info }

$ typed-derive --bind localhost
? failed
error: invalid value 'localhost' for '--bind <BIND>': invalid IP address syntax

For more information, try '--help'.

Time

$ typed-derive --sleep 10s
Args { optimization: None, include: None, bind: None, sleep: Some(Duration(10s)), defines: [], port: 22, log_level: Info }

$ typed-derive --sleep forever
? failed
error: invalid value 'forever' for '--sleep <SLEEP>': expected number at 0

For more information, try '--help'.

Defines (key-value pairs)

$ typed-derive -D Foo=10 -D Alice=30
Args { optimization: None, include: None, bind: None, sleep: None, defines: [("Foo", 10), ("Alice", 30)], port: 22, log_level: Info }

$ typed-derive -D Foo
? failed
error: invalid value 'Foo' for '-D <DEFINES>': invalid KEY=value: no `=` found in `Foo`

For more information, try '--help'.

$ typed-derive -D Foo=Bar
? failed
error: invalid value 'Foo=Bar' for '-D <DEFINES>': invalid digit found in string

For more information, try '--help'.

Discrete numbers

$ typed-derive --port 22
Args { optimization: None, include: None, bind: None, sleep: None, defines: [], port: 22, log_level: Info }

$ typed-derive --port 80
Args { optimization: None, include: None, bind: None, sleep: None, defines: [], port: 80, log_level: Info }

$ typed-derive --port
? failed
error: the argument '--port <PORT>' requires a value but none was supplied
  [possible values: 22, 80]

For more information, try '--help'.

$ typed-derive --port 3000
? failed
error: '3000' isn't a valid value for '--port <PORT>'
  [possible values: 22, 80]

For more information, try '--help'.

Enums from crates that can't implement ValueEnum

$ typed-derive --log-level debug
Args { optimization: None, include: None, bind: None, sleep: None, defines: [], port: 22, log_level: Debug }

$ typed-derive --log-level error
Args { optimization: None, include: None, bind: None, sleep: None, defines: [], port: 22, log_level: Error }

$ typed-derive --log-level
? failed
error: the argument '--log-level <LOG_LEVEL>' requires a value but none was supplied
  [possible values: info, debug, info, warn, error]

For more information, try '--help'.

$ typed-derive --log-level critical
? failed
error: 'critical' isn't a valid value for '--log-level <LOG_LEVEL>'
  [possible values: info, debug, info, warn, error]

For more information, try '--help'.