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

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?

edited Nov 26 '18 at 5:05

sawa

132k29205304

asked Nov 26 '18 at 3:18

Donato

2,11431434

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

add a comment |

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?

edited Nov 26 '18 at 5:05

sawa

132k29205304

asked Nov 26 '18 at 3:18

Donato

2,11431434

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

add a comment |

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?

edited Nov 26 '18 at 5:05

sawa

132k29205304

asked Nov 26 '18 at 3:18

Donato

2,11431434

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

edited Nov 26 '18 at 5:05

sawa

132k29205304

asked Nov 26 '18 at 3:18

Donato

2,11431434

edited Nov 26 '18 at 5:05

sawa

132k29205304

asked Nov 26 '18 at 3:18

Donato

2,11431434

edited Nov 26 '18 at 5:05

sawa

132k29205304

edited Nov 26 '18 at 5:05

sawa

132k29205304

edited Nov 26 '18 at 5:05

sawa

132k29205304

asked Nov 26 '18 at 3:18

Donato

2,11431434

asked Nov 26 '18 at 3:18

Donato

2,11431434

asked Nov 26 '18 at 3:18

Donato

2,11431434

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

add a comment |

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

add a comment |

1 Answer
1

active

oldest

votes

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

edited Nov 26 '18 at 5:03

sawa

132k29205304

answered Nov 26 '18 at 4:51

Lenin Raj Rajasekaran

16k1171114

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

add a comment |

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1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

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

edited Nov 26 '18 at 5:03

sawa

132k29205304

answered Nov 26 '18 at 4:51

Lenin Raj Rajasekaran

16k1171114

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

add a comment |

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

edited Nov 26 '18 at 5:03

sawa

132k29205304

answered Nov 26 '18 at 4:51

Lenin Raj Rajasekaran

16k1171114

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

add a comment |

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

edited Nov 26 '18 at 5:03

sawa

132k29205304

answered Nov 26 '18 at 4:51

Lenin Raj Rajasekaran

16k1171114

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

edited Nov 26 '18 at 5:03

sawa

132k29205304

answered Nov 26 '18 at 4:51

Lenin Raj Rajasekaran

16k1171114

edited Nov 26 '18 at 5:03

sawa

132k29205304

edited Nov 26 '18 at 5:03

sawa

132k29205304

edited Nov 26 '18 at 5:03

sawa

132k29205304

answered Nov 26 '18 at 4:51

Lenin Raj Rajasekaran

16k1171114

answered Nov 26 '18 at 4:51

Lenin Raj Rajasekaran

16k1171114

answered Nov 26 '18 at 4:51

Lenin Raj Rajasekaran

16k1171114

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

add a comment |

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

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

add a comment |

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