class ActiveAdmin::Scope

a default block always returning true will be returned.
Returns the display if block. If the block was not explicitly defined

def display_if_block
  @display_if_block || proc{ true }
end

# => Scope with name 'Published' using a block to scope
Scope.new('Published') { |articles| articles.where(:published => true) }

# => Scope with name 'Published' and scope method :public, optionally displaying the scope per the :if block, using a block
Scope.new('Published', :public, :if => proc { current_admin_user.can?( :manage, active_admin_config.resource_class ) } ) { |articles| articles.where(:published => true) }

# => Scope with name 'Published' and scope method :public
Scope.new('Published', :public)

# => Scope with name 'Published' and scope method :published
Scope.new(:published)

Examples:

Create a Scope

def initialize(name, method = nil, options = {}, &block)
  @name = name.is_a?( String ) ? name : name.to_s.titleize
  @scope_method = method
  # Scope ':all' means no scoping
  @scope_method ||= name.to_sym unless name.to_sym == :all
  @id = @name.gsub(' ', '').underscore
  if block_given?
    @scope_method = nil
    @scope_block = block
  end
  @display_if_block = options[:if]
end