Easy way to check is sub!() succeeds?

ruby-talk
1

But sub! always returns nil, even when it succeeds (in Perl, it will
return the number of substitutions made, enabling "next if
s/\.$suf$//")

Er, no it doesn't.

irb(main):001:0> s="aaabbb"
=> "aaabbb"
irb(main):002:0> s.sub!(/a+/,'')
=> "bbb"
irb(main):003:0> s.sub!(/zzz/,'')
=> nil

C:\>ri String.sub!
------------------------------------------------------------ String#sub!
     str.sub!(pattern, replacement) => str or nil
     str.sub!(pattern) {|match| block } => str or nil

···

------------------------------------------------------------------------
     Performs the substitutions of +String#sub+ in place, returning
     _str_, or +nil+ if no substitutions were performed.

2

Gavin Kistner wrote:

But sub! always returns nil, even when it succeeds (in Perl, it will return the number of substitutions made, enabling "next if s/\.$suf$//")

Er, no it doesn't.

irb(main):001:0> s="aaabbb"
=> "aaabbb"
irb(main):002:0> s.sub!(/a+/,'')
=> "bbb"
irb(main):003:0> s.sub!(/zzz/,'')
=> nil

Ok, that makes more sense. Turns out I was upsetting Ruby's scoping/aliasing. Eventually I got an error "Can't modify frozen string", which tipped me off. Now I have:

    ARGV.each do |file|
       path = file.dup # copy to tweak
       zip.each do |suf, cmd|
          if path.sub!(%r{\.#{suf}$}, '')

And everything works ok. Seems like a loop w/i a loop thing? Anyways, thanks for the sub!() ptr.

-Nate