How to use :symbols when defining task dependencies

rake_helper.rb

# defined the '+' method of Symbol so we can do things like :build+:update_version in the task dependencies and get 'build:update_vesion'
#  Instead of using strings which are hard to refactor
class Symbol
  def method_missing(m, *args, &block)
    if (m == :+)
      return "#{self.to_s}:#{args[0]}"
    else
      super
    end
  end
end

RakeFile.rb

namespace :namespace1 do
  desc "task1"
  task :task1 do
    puts "task1 in namespace1"
  end

  desc "task2"
  task :task2 do
    puts "task2 in namespace1"
  end
end

namespace :namespace2 do
  desc "task1"
  task :task1 do
    puts "task1 in namespace2"
  end

end


desc 'Run all task'
task :run_all => [:namespace1+:task1, :namespace1+:task2, :namespace2+:task1]

RakeFile_old.rb

namespace :namespace1 do
  desc "task1"
  task :task1 do
    puts "task1 in namespace1"
  end
 
  desc "task2"
  task :task2 do
    puts "task2 in namespace1"
  end
end
 
namespace :namespace2 do
  desc "task1"
  task :task1 do
    puts "task1 in namespace2"
  end
 
end
 
 
desc 'Run all task'
task :run_all => ['namespace1:task1', 'namespace1:task2', 'namespace2:task1']