Package cli provides structure for command line applications.

This package is moderately opinionated but I have tried to provide hooks in some key areas. The package is built using variadic options so it is easy to extend.

There exists first class support for only a single level of commands. I wanted to keep the command and flag definitions together. I think it's easier to maintain for small to medium sized applications and it is still easy to break up if the application outgrows that pattern.

I value documentation so I've separated the usage lookup so as to not subtly encourage minimal documentation. A nice side effect of this decision is that it should be relatively straight forward to plug in internationalization support for the built in help command.

Usage of this package gives you the following:

• command router/dispatcher
• flags (global and per-command)
• middleware (global and per-command)
• automatic environment variable flag mappings
• automatic command not found usage and suggestions by levenshtein distance
• automatic default command displays usage
• read from stdin, write to stdout/stderr
• designed to be testable

Custom flag types are easy to implement but I felt the need to depart from the standard library flag package interfaces to provide the developer experience I'm going for. See the FlagKind interface for details.

Explicitly defined flag values on the command line take precedence over environment variables and default values.

Generating shell completion should come eventually.