cligen is a powerful Nim library designed to simplify the creation of command-line interfaces (CLIs) by inferring and generating options and argument parsing directly from proc signatures. Inspired by Python’s argh and designed for ease of use, cligen leverages Nim’s reflection capabilities to create parser-dispatchers that translate command-line inputs into function calls effortlessly.

Key Features

• Minimal Code Requirement: Adding a CLI to a function can be achieved with just one line of code, making it incredibly efficient for developers.

  import cligen; dispatch fun
  

• Automatic Help Generation: Automatically generated help messages provide users with a clear understanding of valid commands and options with minimal effort:

  Usage:
    fun [optional-params] [args: string...]
  Options:
    -h, --help                    print this cligen-erated help
    -f=, --foo=    int     1      set foo
    -b=, --bar=    float   2.0    set bar
    --baz=         string  "x"    set baz
    -v, --verb     bool    false  set verb
  

• Flexible Option Parsing: Utilize any unambiguous prefix for long options and customize help messages, making it user-friendly and adaptable to various command line patterns.
• Custom Parameter Types: Extend parsing capabilities with custom parameter handling, allowing for tailored interactions based on specific user requirements.

Example Usage

Here’s an example of a simple command-line function with cligen:

proc fun(foo=1, bar=2.0, baz="x", verb=false, args: seq[string]): int =
  result = 1  # Placeholder for real logic

dispatch fun

Subcommands Support

cligen also supports subcommands similar to tools like git, allowing for complex command structures with ease:

proc foo(myRequired: int, mynums: seq[int], foo=1) = discard
proc bar(yippee: int, myFlts: seq[float], verb=false) = discard

dispatchMulti([foo], [bar])

Customization Options

Many parameters can be customized, including short option aliases and their help descriptions. Users can also override built-in parsers or provide their own parsing logic to meet specific requirements.

Documentation and Examples

For more information, comprehensive documentation can be found through the following resources:

• User Guide and Documentation
• Example Config File
• Test Suite

By utilizing cligen, developers can create robust command-line interfaces that are efficient, flexible, and easy to manage.