rake cmd line task name alchemy

Rakefile

# Safe little monkey patch to Rake...until it isn't ;)
module Rake
  class Application
    def top_level_tasks=(tasks)
      @top_level_tasks = tasks
    end
  end
end

puts 'Original top level tasks: %s' % Rake.application.top_level_tasks.inspect

Rake.application.top_level_tasks = Rake.application.top_level_tasks.map do |v|
  if v =~ /(ruby)(\d{2})/
    "#{$1}[#{$2}]"
  else
    v
  end
end

puts 'Monkey patched top level tasks: %s' % Rake.application.top_level_tasks.inspect

desc 'build specifed ruby version'
task :ruby, [:version] do |t, args|
  puts "---> building ruby version #{args.version}"
end

task :default do
  puts '---> doing something secret by default'
end

xxx_output

C:\>rake ruby18
Original top level tasks: ["ruby18"]
Monkey patched top level tasks: ["ruby[18]"]
---> building ruby version 18

C:\>rake ruby19
Original top level tasks: ["ruby19"]
Monkey patched top level tasks: ["ruby[19]"]
---> building ruby version 19

C:\>rake ruby20
Original top level tasks: ["ruby20"]
Monkey patched top level tasks: ["ruby[20]"]
---> building ruby version 20

C:\>rake ruby21
Original top level tasks: ["ruby21"]
Monkey patched top level tasks: ["ruby[21]"]
---> building ruby version 21