From: "drbrain (Eric Hodel)" <drbrain@...7.net>
Date: 2013-06-12T06:54:36+09:00
Subject: [ruby-core:55445] [ruby-trunk - Bug #8511] gsub("\\","\\\\") works incorrect


Issue #8511 has been updated by drbrain (Eric Hodel).


=begin
No, it works as expected, please read the documentation for String#gsub:

  If replacement is a String it will be substituted for the
  matched text. It may contain back-references to the pattern's capture groups
  of the form \\\d, where d is a group number, or \\\k<n>,
  where n is a group name. If it is a double-quoted string, both
  back-references must be preceded by an additional backslash. However, within
  replacement the special match variables, such as $&, will not
  refer to the current match.

So your replacement string (({"\\\\"})) replaces with one backslash, not two.  Use:

  "\\".gsub("\\", "\\\\\\\\") #=> "\\\\" (length 2)

=end
----------------------------------------
Bug #8511: gsub("\\","\\\\") works incorrect
https://bugs.ruby-lang.org/issues/8511#change-39868

Author: galnaktar (Oleg K)
Status: Rejected
Priority: Normal
Assignee: 
Category: 
Target version: 
ruby -v: ruby 2.0.0p195 (2013-05-14) [i386-mingw32]
Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN


DL is deprecated, please use Fiddle
irb(main):001:0> a = "\\"
=> "\\"
irb(main):002:0> a.gsub("\\", "\\\\")
=> "\\"
irb(main):003:0> a.gsub("\\", ".")
=> "."
irb(main):004:0> a.gsub(".", "\\\\")
=> "\\"
irb(main):005:0> a = "\\"
=> "\\"
irb(main):006:0> a.gsub("..", "\\\\")
=> "\\"
irb(main):007:0> a.gsub("..", "\\\\")
=> "\\"
irb(main):008:0> "\\".gsub("..", "\\\\")
=> "\\"
irb(main):009:0> "\\".gsub(/./, "\\\\")
=> "\\"
irb(main):010:0> "..".gsub("..", "\\\\")
=> "\\"
irb(main):011:0> "...".gsub("...", "\\\\\\")
=> "\\\\"
irb(main):012:0>


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