Option Types

Many built-in option types are available. These types can either be specified by the class-name or a symbol.

• :flag, :bool, :boolean, TrueClass, FalseClass : a boolean option (also referred to as a "flag"). Value is either true or false
• :int, :integer, Integer : an option that returns an Integer
• :float, :double, Float : an option that returns a Float
• :string, String : an option that returns a String
• :io, IO : an option that returns an opened IO object (typically a file or a URL)
• :date, Date : an option that returns a Date object

Furthermore, Optimist accepts pluralized symbol versions of the above arguments, e.g: :ints, :integers, :floats, :doubles, :strings, :ios, :dates

These plural versions will return an Array of that object type.

Type checking

Type checking and type conversion is performed on the option as it is given. Invalid input will cause an error.

opts = Optimist::options do
  opt :xx, "x opt", :type => :string 
  opt :yy, "y opt", :type => :float
  opt :zz, "z opt", :type => :integer
end

$ ./types.rb -y ABC
Error: option '-y' needs a floating-point number.
$ ./types.rb -z 4.0
Error: option '-z' needs an integer.

Same option, different type conversion

opts = Optimist::options do
  opt :xx, "x opt", :type => :string 
  opt :yy, "y opt", :type => :float
  opt :zz, "z opt", :type => :integer
end
p opts
puts "xx class is #{opts[:xx].class}"
puts "yy class is #{opts[:yy].class}"
puts "zz class is #{opts[:zz].class}"

The same option given on the command-line (e.g.: '4'), is converted into different types depending on the :type.

$ ./types.rb -x 4 -y 4 -z 4
{:xx=>"4", :yy=>4.0, :zz=>4, :help=>false, :xx_given=>true, :yy_given=>true, :zz_given=>true}
xx class is String
yy class is Float
zz class is Fixnum

Customizing types

At this time, there is no way to define custom types. The best known method is to use a :string type and convert the type after the fact.