# Can someone show me how to use ARGV with my class?

**URL:** <https://www.ruby-forum.com/t/can-someone-show-me-how-to-use-argv-with-my-class/120367>\
**Category:** Ruby\
**Created:** [November 16, 2007, 9:02am UTC](https://www.ruby-forum.com/t/can-someone-show-me-how-to-use-argv-with-my-class/120367 "2007-11-16T09:02:21Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![pood](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/3bc359/32.png) [@pood](https://www.ruby-forum.com/u/pood)\
**Post date:** [November 16, 2007, 9:02am UTC](https://www.ruby-forum.com/t/can-someone-show-me-how-to-use-argv-with-my-class/120367/1 "2007-11-16T09:02:21Z")

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I’m trying to write an command line program.

For instance

if I have a class like this with 1 method

# class Coolest Program coolest\_method (a,b) puts a + b end end

How do I program it so it runs in command line?

# so:

# ruby coolest.rb “cool” “est”

it’ll output:

coolest

===

aka insert the 2 arguments into the Coolest Program object? Can’t seem  
to figure this out, been searching the last hour. I get how to use the  
OptionParser library to take options, but not arguments.

---

<div class="post-metadata">

**Author:** ![pood](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/3bc359/32.png) [@pood](https://www.ruby-forum.com/u/pood)\
**Post date:** [November 16, 2007, 9:19am UTC](https://www.ruby-forum.com/t/can-someone-show-me-how-to-use-argv-with-my-class/120367/2 "2007-11-16T09:19:58Z")

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On Behalf Of Feng T.

# it’ll output:

# coolest

this is just a simple example

C:\temp\>cat coolest.rb

def coolest\_method \*args  
p args.join  
end

coolest\_method \*ARGV

C:\temp\>ruby coolest.rb “cool” “est”  
“coolest”

kind regards -botp

---

<div class="post-metadata">

**Author:** ![pood](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/3bc359/32.png) [@pood](https://www.ruby-forum.com/u/pood)\
**Post date:** [November 16, 2007, 9:24am UTC](https://www.ruby-forum.com/t/can-someone-show-me-how-to-use-argv-with-my-class/120367/3 "2007-11-16T09:24:04Z")

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Alle venerdì 16 novembre 2007, Feng T. ha scritto:

> ```
> puts a + b
> 
> ```
> 
> it’ll output:
> 
> coolest
> 
> ===
> 
> aka insert the 2 arguments into the Coolest Program object? Can’t seem  
> to figure this out, been searching the last hour. I get how to use the  
> OptionParser library to take options, but not arguments.

If you don’t need to pass options but only arguments, you don’t need  
OptionParser at all. Command line arguments and options are stored in  
the  
ARGV array. For example, if you do:

ruby my\_program.rb -a --b-with-long-name=3 arg1 arg2

ARGV will be:

["-a", “–b-with-long-name=3”, “arg1”, “arg2”]

In your example case, you can do (note that Coolest Program is not a  
valid  
name for a class):

class CoolestProgram  
coolest\_method (a,b)  
puts a + b  
end  
end

CoolestProgram.coolest\_method(ARGV[0], ARGV[1])

If you need to use OptionParser because you also need options, there are  
two  
situations, depending on whether you use OptionParser#parse! or  
OptionParser#parse. Both methods return the command line arguments, but  
the  
first also changes ARGV removing all the options, so that it will  
contain  
only the arguments.  
For example, take the following script:

#!/usr/bin/env ruby

require ‘optparse’

opts={}

o = OptionParser.new do |o|  
o.on("-v", “–verbose”, “turn on the verbose  
flag”){opts[:verbose]=true}  
end

args = o.parse(ARGV)

puts “opts= #{opts.inspect}”

puts “ARGV= #{ARGV.inspect}”

puts “args= #{args.inspect}”

called with the command:

ruby program.rb -v 1 2 3

outputs:

opts= {:verbose=\>true}  
ARGV= ["-v", “1”, “2”, “3”]  
args= [“1”, “2”, “3”]

If I replace the line o.parse(ARGV) with o.parse!(ARGV), I get

opts= {:verbose=\>true}  
ARGV= [“1”, “2”, “3”]  
args= [“1”, “2”, “3”]

I hope this helps

Stefano