Provides derive(Options) for gumdrop crate

derive(Options)

derive(Options) generates an implementation of the trait Options, creating an option for each field of the decorated struct.

See the gumdrop documentation for an example of its usage.

options attribute

Behavior of derive(Options) can be controlled by adding #[options(...)] attributes to one or more fields within a decorated struct.

Supported items are:

• count marks a field as a counter value. The field will be incremented each time the option appears in the arguments, i.e. field += 1;
• free marks a field as the free argument container. Non-option arguments will be appended to this field using its push method.
• short = "?" sets the short option name to the given character
• no_short prevents a short option from being assigned to the field
• long = "..." sets the long option name to the given string
• no_long prevents a long option from being assigned to the field
• help = "..." sets help text returned from the Options::usage method
• meta = "..." sets the meta variable displayed in usage for options which accept an argument