What's the point of ARGV in Ruby?

Question

What\'s the point of ARGV in Ruby?

first, second, third = ARGV 
puts \"The script is called: #{$0}\"
puts \"Your first variable is: #{first}\"
puts \"Your se         


        

Answer 1

ARGV has a long tradition and comes from the UNIX/POSIX world where most C programs must contain the following:

int main(int argc, char **argv)
{
   return(0);
}

There argc represents the number of arguments supplied, and argv is a low-level pointer to the first of potentially a number of string pointers. The name argv has stuck around in various forms.

Command-line arguments are very popular with developers, though they're usually not used quite as you seem to think. Un-named arguments are much harder to deal with. That's why things like optparse exist to help deal with them.

Here's an example from the OptionParser documentation:

require 'optparse'

options = {}
OptionParser.new do |opts|
  opts.banner = "Usage: example.rb [options]"

  opts.on("-v", "--[no-]verbose", "Run verbosely") do |v|
    options[:verbose] = v
  end
end.parse!

p options
p ARGV

This allows you to define much more usable command-line arguments and then use them. For your example, I'd expect it to work like this:

test_script --live "New York" --computer "Lenovo" --like

That makes it quite obvious what the arguments are because they're named.