def self.record *args
      options = args.extract_options!
      options.reverse_merge!(:export_time => Time.now,
                             :state => "starting")
      begin
        metadata = ExportMetadata.new
        metadata.set_attributes options

        yield metadata
        metadata.store!
      end
    end

      ExportMetadata.record(:table => @export_obj.table_name,
                            :database => @export_obj.source_schema,
                            :filepath => filepath) do |metadata|

        if @export_obj.state == "new"
          initial_export metadata
    end
      end

    def initial_export metadata
      @export_obj.ssh_to_source do |ssh|
        metadata.ssh = ssh
    metadata.store!
      end
    end

-- SSH is set to nil initially in ExportMetadata class
@ssh = nil

-- Store method defined in ExportMetadata class
    def store!
      cmd = "cat #{self.to_json} > #{@filepath}.json"
      @ssh.exec!(cmd)
    end


Calling initial_export throws an exception because @ssh is nil. But it should not be nil, I set in the block:

initial_export(metadata)
NoMethodError: undefined method `exec!' for nil:NilClass