I’m not sure how many gems/libraries there are in Ruby to parse command line arguments, but today I discovered a new one: CLAP.
Most of the time when I’m writing a script, all I need to do is get one or two arguments from the command line and maybe print a usage message. To be honest I never mastered the OptionParser class, it just seems like overkill when writing a small script.
So most of the time I cheat and do something like this:
def main(filename)
puts "filename = #{filename}"
end
if __FILE__ == $PROGRAM_NAME
if ARGV[0]
main(ARGV[0])
else
puts "usage: ruby #{__FILE__} FILENAME"
end
end
Now with CLAP I can add some real options.
require 'rubygems'
require 'clap'
def usage
puts "usage: ruby #{__FILE__} --file FILENAME"
end
def main(filename, verbose=false)
puts "filename = #{filename}"
puts "verbose = #{verbose}"
end
if __FILE__ == $PROGRAM_NAME
# set defaults
verbose = false
filename = nil
# parse the command line
Clap.run ARGV,
"-v" => lambda { verbose = true },
"-f" => lambda { |arg| filename = arg },
"--file" => lambda { |arg| filename = arg }
# execute
main(filename, verbose) unless filename.nil?
usage if filename.nil?
end
