8 files changed, 14 insertions, 14 deletions
diff --git a/lib/axlsx/drawing/area_series.rb b/lib/axlsx/drawing/area_series.rb
index cf4aaf13..afaf5ea0 100644
--- a/lib/axlsx/drawing/area_series.rb
+++ b/lib/axlsx/drawing/area_series.rb
@@ -89,7 +89,7 @@ module Axlsx
         if !@show_marker
           str << '<c:marker><c:symbol val="none"/></c:marker>'
         elsif @marker_symbol != :default
-          str << '<c:marker><c:symbol val="' + @marker_symbol.to_s + '"/></c:marker>'
+          str << '<c:marker><c:symbol val="' << @marker_symbol.to_s << '"/></c:marker>'
         end
 
         @labels.to_xml_string(str) unless @labels.nil?
diff --git a/lib/axlsx/drawing/line_series.rb b/lib/axlsx/drawing/line_series.rb
index fbed4000..4854a718 100644
--- a/lib/axlsx/drawing/line_series.rb
+++ b/lib/axlsx/drawing/line_series.rb
@@ -89,7 +89,7 @@ module Axlsx
         if !@show_marker
           str << '<c:marker><c:symbol val="none"/></c:marker>'
         elsif @marker_symbol != :default
-          str << '<c:marker><c:symbol val="' + @marker_symbol.to_s + '"/></c:marker>'
+          str << '<c:marker><c:symbol val="' << @marker_symbol.to_s << '"/></c:marker>'
         end
 
         @labels.to_xml_string(str) unless @labels.nil?
diff --git a/lib/axlsx/drawing/pie_series.rb b/lib/axlsx/drawing/pie_series.rb
index f3edd1e9..cce79648 100644
--- a/lib/axlsx/drawing/pie_series.rb
+++ b/lib/axlsx/drawing/pie_series.rb
@@ -46,7 +46,7 @@ module Axlsx
     # @return [String]
     def to_xml_string(str = +'')
       super(str) do
-        str << '<c:explosion val="' + @explosion.to_s + '"/>' unless @explosion.nil?
+        str << '<c:explosion val="' << @explosion.to_s << '"/>' unless @explosion.nil?
         colors.each_with_index do |c, index|
           str << '<c:dPt>'
           str << '<c:idx val="' << index.to_s << '"/>'
diff --git a/lib/axlsx/drawing/scatter_series.rb b/lib/axlsx/drawing/scatter_series.rb
index 9c6e12f2..9e3579f7 100644
--- a/lib/axlsx/drawing/scatter_series.rb
+++ b/lib/axlsx/drawing/scatter_series.rb
@@ -121,7 +121,7 @@ module Axlsx
       if !@show_marker
         '<c:symbol val="none"/>'
       elsif @marker_symbol != :default
-        '<c:symbol val="' + @marker_symbol.to_s + '"/>'
+        '<c:symbol val="' << @marker_symbol.to_s << '"/>'
       end.to_s
     end
   end
diff --git a/lib/axlsx/stylesheet/color.rb b/lib/axlsx/stylesheet/color.rb
index 24fe3bc3..0c40a073 100644
--- a/lib/axlsx/stylesheet/color.rb
+++ b/lib/axlsx/stylesheet/color.rb
@@ -73,7 +73,7 @@ module Axlsx
     # @param [String] str
     # @return [String]
     def to_xml_string(str = +'', tag_name = 'color')
-      serialized_tag('' + tag_name + '', str)
+      serialized_tag(tag_name.to_s, str)
     end
   end
 end
diff --git a/lib/axlsx/util/constants.rb b/lib/axlsx/util/constants.rb
index 459e0099..0767be31 100644
--- a/lib/axlsx/util/constants.rb
+++ b/lib/axlsx/util/constants.rb
@@ -239,25 +239,25 @@ module Axlsx
   COMMENT_PN = "comments%d.xml"
 
   # location of schema files for validation
-  SCHEMA_BASE = (File.dirname(__FILE__) + '/../../schema/').freeze
+  SCHEMA_BASE = "#{File.dirname(__FILE__)}/../../schema/"
 
   # App validation schema
-  APP_XSD = (SCHEMA_BASE + "shared-documentPropertiesExtended.xsd").freeze
+  APP_XSD = "#{SCHEMA_BASE}shared-documentPropertiesExtended.xsd"
 
   # core validation schema
-  CORE_XSD = (SCHEMA_BASE + "opc-coreProperties.xsd").freeze
+  CORE_XSD = "#{SCHEMA_BASE}opc-coreProperties.xsd"
 
   # content types validation schema
-  CONTENT_TYPES_XSD = (SCHEMA_BASE + "opc-contentTypes.xsd").freeze
+  CONTENT_TYPES_XSD = "#{SCHEMA_BASE}opc-contentTypes.xsd"
 
   # rels validation schema
-  RELS_XSD = (SCHEMA_BASE + "opc-relationships.xsd").freeze
+  RELS_XSD = "#{SCHEMA_BASE}opc-relationships.xsd"
 
   # spreadsheetML validation schema
-  SML_XSD = (SCHEMA_BASE + "sml.xsd").freeze
+  SML_XSD = "#{SCHEMA_BASE}sml.xsd"
 
   # drawing validation schema
-  DRAWING_XSD = (SCHEMA_BASE + "dml-spreadsheetDrawing.xsd").freeze
+  DRAWING_XSD = "#{SCHEMA_BASE}dml-spreadsheetDrawing.xsd"
 
   # number format id for pecentage formatting using the default formatting id.
   NUM_FMT_PERCENT = 9
diff --git a/lib/axlsx/workbook/worksheet/dimension.rb b/lib/axlsx/workbook/worksheet/dimension.rb
index 42e02e72..f27404b6 100644
--- a/lib/axlsx/workbook/worksheet/dimension.rb
+++ b/lib/axlsx/workbook/worksheet/dimension.rb
@@ -39,7 +39,7 @@ module Axlsx
     def to_xml_string(str = +'')
       return if worksheet.rows.empty?
 
-      str << "<dimension ref=\"%s\"></dimension>" % sqref
+      str << '<dimension ref="' << sqref << '"></dimension>'
     end
 
     # The first cell in the dimension
diff --git a/lib/axlsx/workbook/worksheet/worksheet.rb b/lib/axlsx/workbook/worksheet/worksheet.rb
index 8c6e53b4..aaeadb11 100644
--- a/lib/axlsx/workbook/worksheet/worksheet.rb
+++ b/lib/axlsx/workbook/worksheet/worksheet.rb
@@ -45,7 +45,7 @@ module Axlsx
     # The name of the worksheet
     # @return [String]
     def name
-      @name ||= "Sheet" + (index + 1).to_s
+      @name ||= "Sheet#{index + 1}"
     end
 
     # Whether to treat values starting with an equals sign as formulas or as literal strings.