Bug #11803: NoMethodError when calling String#gsub

• Status: Rejected
• Assignee: matz (Yukihiro Matsumoto)
• Target version: -
• ruby -v: ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-darwin14]
• Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN

Assigning the result of a call to String#gsub throws a NoMethodError. It seems to have to do with assigning the return value to a variable with the same name as the method returning the string gsub is called on. I've included short script which reproduces the issue.

• File test_fail.rb test_fail.rb added

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Rejected

  def to_s
    return unless word
    word = word.gsub(/a/, "")

You make a new local variable here, and call gsub on it before assignment.

[Hanmac (Hans Mackowiak)]

first i dont think its a good idea in a to_s method to change the value of the object.
otherwise you need to use @instance variables then it works:

class TestFail
  def initialize(word)
    @word = word
  end

  def to_s
    return unless @word
    @word.gsub(/a/, "")
  end

  def word
    @word
  end
end