Variable in Thor desc

With a cli project I would like to have a shared super class with thor tasks. When calling the sub-command help it should expose the shared command with a custom description.

I came up with the code below, but the variable @plural is not substituted in the description.

Is this possible with Thor and some meta programming?

module MyModule
  class ResourceSubcommand < Thor

    def initialize(*args)
      super
    end

    desc "list", "list all #{@plural}"
    def list
      list_object(@default_list_columns)
    end
  end
end

module MyModule
  class Account < MyModule::ResourceSubcommand

    def initialize(*args)
      super
      @plural = 'accounts'
    end

  end
end

module MyModule
  class Commands < Thor

    desc "account SUBCOMMAND ...ARGS", "manage Exact Online accounts"
    subcommand "account", Account

  end
end

running $ thorcli account help should output:

Commands:
  thorcli account help [COMMAND]     # Describe subcommands or one specific subcommand
  thorcli account list               # list all accounts

Solution

The string passed to desc is evaluated in the context of the class, but the initialize method is evaluated in the context of instances, so the two @plural belong to two different objects.

Further more, desc is called immediately when defining the superclass MyModule::ResourceSubcommand, and there is no easy way to postpone its evaluation after the superclass gets inherited and the @plural in the subclass is set, your goal seems very hard to achieve.

P.S. I've tried overriding MyModule::ResourceSubcommand::inherited, and MyModule::ResourceSubcommand.singleton_class::inherited, and I failed. Maybe you could define MyModule::ResourceSubcommand as a module, override its self.included, and include it after setting @plural in the subclass.

UPDATE

I finally succeed. Here is my solution:

module MyModule

  # Change from class to module
  module ResourceSubcommand

    # A hook called when this module is included by other modules
    def self.included(base)
      base.class_eval do
        desc "list", "list all #{@plural}"
        def list
          list_object(@default_list_columns)
        end
      end
    end
  end
end

module MyModule

  # No inheritance
  class Account

    # Don't put this in any instance methods, including #initialize
    @plural = 'accounts'

    # Be sure to include after @plural is set
    include ResourceSubcommand
  end
end