Parse arg

Traits and implementations for parsing command-line arguments.

About

This crate provides traits and implementations for parsing command-line arguments. 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.

Since matching both --foo VAL and --foo=VAL arguments is common and it's not an easy task to implement on top of OsStr, due to limitation of std, this crate also provides a function to match and parse such arguments.

Further, since many programs support -xVAL style parameters and short switches grouped into a single argument, which isn't easy to achieve using OsStr either, this crate provides a helper for this too.

Contibutions

I will merge new implementations liberally, provided these conditions are met:

• The type is either in std or in another crate which is added as an optional dependency.
• The description of the type is gramatically correct, readable explanation of the type, that can be appended to the string "The input must be " without sounding unnatural.
• The user must be able to know how to formt the input based on the description without any googling. In case of doubt provide more precise description in parentheses.
• Your contribution is licensed under MIT or MITNFA license.

License

MITNFA