lib/osheet/worksheet.rb in osheet-0.2.0 vs lib/osheet/worksheet.rb in osheet-0.3.0

@@ -14,14 +14,23 @@
       @name = nil
       instance_exec(*args, &block) if block_given?
     end
 
     def name(value=nil)
-      !value.nil? ? @name = value : @name
+      !value.nil? ? @name = sanitized_name(value) : @name
     end
 
     def attributes
       { :name => @name }
+    end
+
+    private
+
+    def sanitized_name(name_value)
+      if @workbook && @workbook.worksheets.collect{|ws| ws.name}.include?(name_value)
+        raise ArgumentError, "the sheet name '#{name_value}' is already in use.  choose a sheet name that is not used by another sheet"
+      end
+      name_value
     end
 
   end
 end