in Ruby, OptionParser returns boolean instead of input values

Question

I'm trying to take the argument values using OptionParser. Instead of values, my code is returning only boolean:

require 'optparse'

options ={}
opts = OptionParser.new do |opts|
opts.on('-v')    { |version| options[:version] = version }
opts.on('-g')    { |branch| options[:branch] = branch }
opts.on('-f')    { |full| options[:full] = full }
opts.on('-h')    { RDoc::usage }
end.parse!

# mandatory options
if (options[:version] == nil)  or (options[:branch] == nil) or (options[:full]== nil) then
    puts options[:branch]
    puts options[:version]
    puts options[:full]
    RDoc::usage('usage')
end

puts options[:branch]

---> TRUE

Any idea?

tadman · Accepted Answer · 2016-04-28 09:08:05Z

4

If you want to capture a value you need to ask for it:

opts = OptionParser.new do |opts|
opts.on('-v=s') { |version| options[:version] = version }
opts.on('-g=s') { |branch| options[:branch] = branch }
opts.on('-f=s') { |full| options[:full] = full }
opts.on('-h') { RDoc::usage }

The =s notation means there's an associated value.

When defining interfaces like this don't forget to include long-form names for clarity like --version or --branch so people don't have to remember g means "branch".

All of this is covered in the fantastic documentation which I encourage you to read.

answered Apr 28, 2016 at 9:08

tadman

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4 Comments

Keith Bennett Over a year ago

Also, of course, the term 's' should be replaced with something meaningful, e.g. 'branch' for '-g'. Remember that the help text will be created using these option specifications.

Keith Bennett Over a year ago

Also, as an aside, OpenStructs are great for storing these options. No need to explicitly refer to hash keys nor to specify in advance attribute names (as would be necessary with Struct.

tadman Over a year ago

@KeithBennett A great point there. Like --version=version is better than -v=s. OpenStruct can keep things pretty clean if you like, but there's nothing entirely wrong with a regular Hash.

Ilya Over a year ago

really fantastic document, +1 :)))))))

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