Crate parse_arg

This crate provides traits to bridge various libraries providing parsable types with libraries providing command line parsing implementations. The core of the crate is ParseArg trait. It works much like FromStr trait, but with these differences:

• It operates on &OsStr instead of &str, thus allowing wider range of possible inputs.
• It provides parse_owned_arg() method which can be specialized to avoid allocations.
• It requires the implementor to provide describe_type() to print human-readable description. of expected input.
• It requires the error type to implement Display in order to enable user-friendly interface.

Further, the crate provides ParseArgFromStr trait, which causes any type implementing it to auto-implement ParseArg trait. This is handy when implementing ParseArg for types that already have FromStr implemented, so that boilerplate is reduced.

Any libraries that wish to help their consumers implement parsing their types from command line may add this crate as an optional dependency and implement the ParseArg trait (directly or indirectly) for their types.

Any binaries wishing to use these traits should enable the parse_arg feature of the librariess that use this crate and use a CLI parses implementation crate that uses it too. Currently the only known implementation is configure_me which is also capable of parsing configuration files.

MSRV

The minimum supported Rust version of the crate is 1.63 and will always be whichever Rust version the current Debian stable (12 - Bookworm at the time of writing) supports.

Enums

ParseArgError

Possible error when parsing certain arguments.

Traits

ParseArg

Defines an interface for types that can be created by parsing command-line argument.

ParseArgFromStr

Shorthand for implementing ParseArg for types that already implement FromStr.