From: "Weirich, James" <James.Weirich@...>
Date: 2003-12-17T05:27:05+09:00
Subject: Re: substituting apostrphe's

From: Peter [mailto:Peter.Vanbroekhoven@cs.kuleuven.ac.be] 
> > irb(main):003:0> a = "a"
> > => "a"
> > irb(main):004:0> a.gsub(/a/, '\'')
> > => "'"
> > irb(main):007:0> a = "abc"
> > => "abc"
> > irb(main):008:0> a.gsub(/a/, '\\\'')
> 
> Did it again... The last line gives "bcbc" as result.

I had a wanted to replace a single apostrophe with an backslash+apostrophe.
E.g. "don't" => "don\\'t" (where \\ is a single backslash in a string).

My initial attempt gave strange results ....

  a = "don't"
  a.sub(/'/, "\\'")   # => "dontt"

Backslash-apostrophe is a special replacement pattern that represents the
part of the string following the match, in this case the letter 't'.  

It took four backslashes to get it to work.

  a.sub(/'/, "\\\\'")   # => "don\\'t"

I'm embarassed to say how long it took me to figure that out. 

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