ARGV processers: how to define command "foo" which is invoked by any unambiguous prefix

I'd like to define a command line app "cla" with commands "foo", "bar", and "find" such that:

./cla foo and ./cla fo both invoke the method defined for foo

./cla find and ./cla fi both invoke find

./cla bar and ./cla b both invoke the method defined for bar

./cla f throws an error

Or something reasonably similar. Hopefully this is clear.

It's not obvious that this can be done in Thor or Commander. I haven't looked at Slop. Do any of the ARGV processor libraries have this ability? Can somebody tell me which libraries, and point me to documentation of the feature?

EDIT: To be clear, I'm not asking for help solving the specific problem above. I'm asking whether it is possible (and not too difficult) to do it with one of the standard command line app builder libraries, which provide many useful features I want besides the ability to invoke a command by a prefix of its name.

Solution

Actually, it seems that thor automatically does what you want out of the box. Specifically, it executes the appropriate command if the shortened form unambiguously matches.

Given this trivial example:

#!/usr/bin/env ruby

require "thor"

class CLA < Thor
  desc "foo", 'Says "foo"'
  def foo
    puts "foo"
  end

  desc "find", 'Says "find"'
  def find
    puts "find"
  end

  desc "bar", 'Says "bar"'
  def bar
    puts "bar"
  end
end

CLA.start

Then:

$ ./cla fo
foo
$ ./cla f
Ambiguous command f matches [find, foo]
$ ./cla fi
find
$ ./cla b
bar

If you really want "f" to always map to "foo" and not give the ambiguous command error, use map like this:

desc "foo", 'Says "foo"'
def foo
  puts "foo"
end
map "f" => :foo

And then this now works:

$ ./cla f
foo