From: Jeremy Wells <jwells@...>
Date: 2006-11-24T03:50:00+09:00
Subject: Re: double-slashes in input causing trouble

Edwin Fine wrote:
> Makes no difference. String#sub states that metacharacters in the 
> pattern will not be interpreted if the pattern is a String and not a 
> Regexp.
>
> Check it out:
>
> irb(main):061:0> x
> => "section 
> header\nkjhKAJSHDKjashdkjASH\\\\\\\\\\\\\\\\KJahfdkasjhdfkajshdfjh\nsection 
> footer"
> irb(main):062:0> y
> => "\nkjhKAJSHDKjashdkjASH\\\\\\\\\\\\\\\\KJahfdkasjhdfkajshdfjh\n"
> irb(main):063:0> z
> => "xyzzy 
> \nkjhKAJSHDKjashdkjASH\\\\\\\\\\\\\\\\KJahfdkasjhdfkajshdfjh\n"
> irb(main):064:0> x.sub(y,z)
> => "section headerxyzzy 
> \nkjhKAJSHDKjashdkjASH\\\\\\\\KJahfdkasjhdfkajshdfjh\nsection footer"
> irb(main):065:0> x.sub(Regexp.new(Regexp.quote(y)),z)
> => "section headerxyzzy 
> \nkjhKAJSHDKjashdkjASH\\\\\\\\KJahfdkasjhdfkajshdfjh\nsection footer"
>
> Identical results.
>
> The problem is that the backslashes in the REPLACEMENT string are being 
> interpreted.
>
> The way to overcome this is to use the block form of sub:
>
> new_body = body.sub(original_section) {|s| s = new_section}
>   
Thanks, I might try that, it's better looking than my solution, which was:
m = Regexp.new("(" + Regexp.escape(original_section) + ")").match(body)
body[(m.begin(1)..m.end(1)-1)] = new_section