Using `gsub` inside (double quoted) heredoc does not work












2















It appears that using gsub inside a (double quoted) heredoc does not evaluate the result of gsub, as follows:



class Test

  def self.define_phone

    class_eval <<-EOS

      def _phone=(val)

        puts val

        puts val.gsub(/D/,'')

      end

    EOS

  end

end



Test.define_phone

test = Test.new

test._phone = '123-456-7890'

# >> 123-456-7890

# >> 123-456-7890


The second puts should have printed 1234567890, just as it would in this case:



'123-456-7890'.gsub(/D/,'')

 # => "1234567890"


What is going on inside the heredoc?






ruby literals heredoc







share|improve this question

























  • Note that you can accomplish this without class eval (and thus no worrying about string escaping). Just replace the class_eval and def _phone with define_method :_phone do |val|

    – Max
    Nov 26 '18 at 14:46
















2















It appears that using gsub inside a (double quoted) heredoc does not evaluate the result of gsub, as follows:



class Test

  def self.define_phone

    class_eval <<-EOS

      def _phone=(val)

        puts val

        puts val.gsub(/D/,'')

      end

    EOS

  end

end



Test.define_phone

test = Test.new

test._phone = '123-456-7890'

# >> 123-456-7890

# >> 123-456-7890


The second puts should have printed 1234567890, just as it would in this case:



'123-456-7890'.gsub(/D/,'')

 # => "1234567890"


What is going on inside the heredoc?






ruby literals heredoc







share|improve this question

























  • Note that you can accomplish this without class eval (and thus no worrying about string escaping). Just replace the class_eval and def _phone with define_method :_phone do |val|

    – Max
    Nov 26 '18 at 14:46














2












2








2








It appears that using gsub inside a (double quoted) heredoc does not evaluate the result of gsub, as follows:



class Test

  def self.define_phone

    class_eval <<-EOS

      def _phone=(val)

        puts val

        puts val.gsub(/D/,'')

      end

    EOS

  end

end



Test.define_phone

test = Test.new

test._phone = '123-456-7890'

# >> 123-456-7890

# >> 123-456-7890


The second puts should have printed 1234567890, just as it would in this case:



'123-456-7890'.gsub(/D/,'')

 # => "1234567890"


What is going on inside the heredoc?






ruby literals heredoc







share|improve this question
















It appears that using gsub inside a (double quoted) heredoc does not evaluate the result of gsub, as follows:



class Test

  def self.define_phone

    class_eval <<-EOS

      def _phone=(val)

        puts val

        puts val.gsub(/D/,'')

      end

    EOS

  end

end



Test.define_phone

test = Test.new

test._phone = '123-456-7890'

# >> 123-456-7890

# >> 123-456-7890


The second puts should have printed 1234567890, just as it would in this case:



'123-456-7890'.gsub(/D/,'')

 # => "1234567890"


What is going on inside the heredoc?






ruby literals heredoc




ruby literals heredoc






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Nov 26 '18 at 5:05









sawa

133k29206308




133k29206308










asked Nov 26 '18 at 3:18









DonatoDonato

2,13931435




2,13931435













  • Note that you can accomplish this without class eval (and thus no worrying about string escaping). Just replace the class_eval and def _phone with define_method :_phone do |val|

    – Max
    Nov 26 '18 at 14:46



















  • Note that you can accomplish this without class eval (and thus no worrying about string escaping). Just replace the class_eval and def _phone with define_method :_phone do |val|

    – Max
    Nov 26 '18 at 14:46

















Note that you can accomplish this without class eval (and thus no worrying about string escaping). Just replace the class_eval and def _phone with define_method :_phone do |val|

– Max
Nov 26 '18 at 14:46





Note that you can accomplish this without class eval (and thus no worrying about string escaping). Just replace the class_eval and def _phone with define_method :_phone do |val|

– Max
Nov 26 '18 at 14:46












1 Answer
1






active

oldest

votes


















5














The problem is with the D in the regex. It will be evaluated when the heredoc is evaluated as a string, which results in D:



"D" # => "D"

eval("/D/") #=> /D/


On the other hand, D inside a single quote will not be evaluated as D:



'D' # => "\D"

eval('/D/') # => /D/


So wrap the heredoc terminator EOS in a single quote to achieve what you want:



class Test

  def self.define_phone

    class_eval <<-'EOS'

      def _phone=(val)

        puts val

        puts val.gsub(/D/,'')

      end

    EOS

  end

end



Test.define_phone

test = Test.new

test._phone = '123-456-7890'

# >> 123-456-7890

# >> 1234567890


Reference



If you run the above code without the wrapped EOS, gsub will try to replace "D" (literally) in the val. See this:



test._phone = '123-D456-D7890DD'

# >> 123-D456-D7890DD

# >> 123-456-7890





share|improve this answer





















  • 3





    Or, another way is to replace D with \D.

    – sawa
    Nov 26 '18 at 4:54











  • Official reference: Literals - Here Documents

    – Stefan
    Nov 26 '18 at 9:12











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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









5














The problem is with the D in the regex. It will be evaluated when the heredoc is evaluated as a string, which results in D:



"D" # => "D"

eval("/D/") #=> /D/


On the other hand, D inside a single quote will not be evaluated as D:



'D' # => "\D"

eval('/D/') # => /D/


So wrap the heredoc terminator EOS in a single quote to achieve what you want:



class Test

  def self.define_phone

    class_eval <<-'EOS'

      def _phone=(val)

        puts val

        puts val.gsub(/D/,'')

      end

    EOS

  end

end



Test.define_phone

test = Test.new

test._phone = '123-456-7890'

# >> 123-456-7890

# >> 1234567890


Reference



If you run the above code without the wrapped EOS, gsub will try to replace "D" (literally) in the val. See this:



test._phone = '123-D456-D7890DD'

# >> 123-D456-D7890DD

# >> 123-456-7890





share|improve this answer





















  • 3





    Or, another way is to replace D with \D.

    – sawa
    Nov 26 '18 at 4:54











  • Official reference: Literals - Here Documents

    – Stefan
    Nov 26 '18 at 9:12
















5














The problem is with the D in the regex. It will be evaluated when the heredoc is evaluated as a string, which results in D:



"D" # => "D"

eval("/D/") #=> /D/


On the other hand, D inside a single quote will not be evaluated as D:



'D' # => "\D"

eval('/D/') # => /D/


So wrap the heredoc terminator EOS in a single quote to achieve what you want:



class Test

  def self.define_phone

    class_eval <<-'EOS'

      def _phone=(val)

        puts val

        puts val.gsub(/D/,'')

      end

    EOS

  end

end



Test.define_phone

test = Test.new

test._phone = '123-456-7890'

# >> 123-456-7890

# >> 1234567890


Reference



If you run the above code without the wrapped EOS, gsub will try to replace "D" (literally) in the val. See this:



test._phone = '123-D456-D7890DD'

# >> 123-D456-D7890DD

# >> 123-456-7890





share|improve this answer





















  • 3





    Or, another way is to replace D with \D.

    – sawa
    Nov 26 '18 at 4:54











  • Official reference: Literals - Here Documents

    – Stefan
    Nov 26 '18 at 9:12














5












5








5







The problem is with the D in the regex. It will be evaluated when the heredoc is evaluated as a string, which results in D:



"D" # => "D"

eval("/D/") #=> /D/


On the other hand, D inside a single quote will not be evaluated as D:



'D' # => "\D"

eval('/D/') # => /D/


So wrap the heredoc terminator EOS in a single quote to achieve what you want:



class Test

  def self.define_phone

    class_eval <<-'EOS'

      def _phone=(val)

        puts val

        puts val.gsub(/D/,'')

      end

    EOS

  end

end



Test.define_phone

test = Test.new

test._phone = '123-456-7890'

# >> 123-456-7890

# >> 1234567890


Reference



If you run the above code without the wrapped EOS, gsub will try to replace "D" (literally) in the val. See this:



test._phone = '123-D456-D7890DD'

# >> 123-D456-D7890DD

# >> 123-456-7890





share|improve this answer















The problem is with the D in the regex. It will be evaluated when the heredoc is evaluated as a string, which results in D:



"D" # => "D"

eval("/D/") #=> /D/


On the other hand, D inside a single quote will not be evaluated as D:



'D' # => "\D"

eval('/D/') # => /D/


So wrap the heredoc terminator EOS in a single quote to achieve what you want:



class Test

  def self.define_phone

    class_eval <<-'EOS'

      def _phone=(val)

        puts val

        puts val.gsub(/D/,'')

      end

    EOS

  end

end



Test.define_phone

test = Test.new

test._phone = '123-456-7890'

# >> 123-456-7890

# >> 1234567890


Reference



If you run the above code without the wrapped EOS, gsub will try to replace "D" (literally) in the val. See this:



test._phone = '123-D456-D7890DD'

# >> 123-D456-D7890DD

# >> 123-456-7890






share|improve this answer














share|improve this answer



share|improve this answer








edited Nov 26 '18 at 5:03









sawa

133k29206308




133k29206308










answered Nov 26 '18 at 4:51









Lenin Raj RajasekaranLenin Raj Rajasekaran

16.1k1173115




16.1k1173115








  • 3





    Or, another way is to replace D with \D.

    – sawa
    Nov 26 '18 at 4:54











  • Official reference: Literals - Here Documents

    – Stefan
    Nov 26 '18 at 9:12














  • 3





    Or, another way is to replace D with \D.

    – sawa
    Nov 26 '18 at 4:54











  • Official reference: Literals - Here Documents

    – Stefan
    Nov 26 '18 at 9:12








3




3





Or, another way is to replace D with \D.

– sawa
Nov 26 '18 at 4:54





Or, another way is to replace D with \D.

– sawa
Nov 26 '18 at 4:54













Official reference: Literals - Here Documents

– Stefan
Nov 26 '18 at 9:12





Official reference: Literals - Here Documents

– Stefan
Nov 26 '18 at 9:12




















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