# Build a hash from ARGV, the Ruby way **URL:** \ **Category:** Ruby\ **Created:** [January 26, 2010, 12:00am UTC](https://www.ruby-forum.com/t/build-a-hash-from-argv-the-ruby-way/182281 "2010-01-26T00:00:23Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![tobyr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/ebca7d/32.png) [@tobyr](https://www.ruby-forum.com/u/tobyr)\ **Post date:** [January 26, 2010, 12:00am UTC](https://www.ruby-forum.com/t/build-a-hash-from-argv-the-ruby-way/182281/1 "2010-01-26T00:00:23Z")
I would like to build a hash from ARGV using UNIX type notation ie any argument which begins with a hyphen or double hyphen is an option and may have as value(s) the argument(s) which succeed it (if they don’t have hyphens). Options without values should result in a hash element which has a key and a dummy value (say “0”). I suspect/hope there is a very simple “Ruby way” to do this, but I got stuck thinking how to look ahead when iterating through ARGV. I’ve got a bodged method of just taking pairs eg -a 1 -b 0 -c 3 etc, but it would be nice to it properly. Any suggestions? All help appreciated! ---
**Author:** ![tobyr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/ebca7d/32.png) [@tobyr](https://www.ruby-forum.com/u/tobyr)\ **Post date:** [January 26, 2010, 12:41am UTC](https://www.ruby-forum.com/t/build-a-hash-from-argv-the-ruby-way/182281/2 "2010-01-26T00:41:02Z")
On Jan 25, 6:00 pm, Toby R. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > I would like to build a hash from ARGV using UNIX type notation ie any > argument which begins with a hyphen or double hyphen is an option and > may have as value(s) the argument(s) which succeed it (if they don’t > have hyphens). Options without values should result in a hash element > which has a key and a dummy value (say “0”). > > I suspect/hope there is a very simple “Ruby way” to do this, but I got > stuck thinking how to look ahead when iterating through ARGV. I’ve got > a bodged method of just taking pairs eg -a 1 -b 0 -c 3 etc, but it would > be nice to it properly. Any suggestions? All help appreciated! $ gem install facets $ irb > require ‘facets/argvector’ > argv = Argvector.new(“-a 0 -b 0 -c 3”) > argv.options ---
**Author:** ![tobyr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/ebca7d/32.png) [@tobyr](https://www.ruby-forum.com/u/tobyr)\ **Post date:** [January 26, 2010, 11:25am UTC](https://www.ruby-forum.com/t/build-a-hash-from-argv-the-ruby-way/182281/3 "2010-01-26T11:25:44Z")
Toby R. wrote: > I would like to build a hash from ARGV using UNIX type notation ie any > argument which begins with a hyphen or double hyphen is an option and > may have as value(s) the argument(s) which succeed it (if they don’t > have hyphens). Options without values should result in a hash element > which has a key and a dummy value (say “0”). Take a look at optparse.rb in the standard ruby library: [http://ruby-doc.org/stdlib/libdoc/optparse/rdoc/classes/OptionParser.html](http://ruby-doc.org/stdlib/libdoc/optparse/rdoc/classes/OptionParser.html) Then if you don’t like that, there are several other libraries that other people have written with more “object like” APIs and very forgettable names. One I came across recently was thor: > **[GitHub - rails/thor: Thor is a toolkit for building powerful command-line...](https://github.com/rails/thor)** > > Thor is a toolkit for building powerful command-line interfaces. - GitHub - rails/thor: Thor is a toolkit for building powerful command-line interfaces. ---
**Author:** ![tobyr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/ebca7d/32.png) [@tobyr](https://www.ruby-forum.com/u/tobyr)\ **Post date:** [January 26, 2010, 11:37am UTC](https://www.ruby-forum.com/t/build-a-hash-from-argv-the-ruby-way/182281/4 "2010-01-26T11:37:38Z")
Brian C. wrote: > Then if you don’t like that, there are several other libraries that > other people have written with more “object like” APIs and very > forgettable names. [http://www.rubyinside.com/trollop-command-line-option-parser-for-ruby-944.html](http://www.rubyinside.com/trollop-command-line-option-parser-for-ruby-944.html) (and some other alternatives are given in the body and the comments) ---
**Author:** ![tobyr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/ebca7d/32.png) [@tobyr](https://www.ruby-forum.com/u/tobyr)\ **Post date:** [January 26, 2010, 7:09pm UTC](https://www.ruby-forum.com/t/build-a-hash-from-argv-the-ruby-way/182281/5 "2010-01-26T19:09:06Z")
Reformatted excerpts from Toby R.'s message of 2010-01-25: > I suspect/hope there is a very simple “Ruby way” to do this, but I got > stuck thinking how to look ahead when iterating through ARGV. I’ve > got a bodged method of just taking pairs eg -a 1 -b 0 -c 3 etc, but it > would be nice to it properly. Any suggestions? All help appreciated! You can start doing something simple with ARGV.each\_slice(2), but any kind of error checking quickly gets complicated. Trollop will do this exact thing for you (turn ARGV into a hash with error checking).