Ruby add method!(with exclamation mark) to string

Question

I have found many resources how to do add "ordinary" method to String.

But i haven't found any info how to add "destructive" method with exclamation mark to String class.

Can somebody rewrite this method to "destructive one"?

def nextval
  case self
  when "A"
    return "B"
  when "B"
    return "C"
  # etc
  end
end

[this example is very simple, i want to add more complex method to String]

I want to achive something like sub and sub! methods.

You'll need to be more specific. You can probably only mutate the things that are exposed publicly, unless you delve into private APIs, which most likely will just come back to haunt you ;) — d11wtq, Oct 22 '11 at 15:31
Do you mean you want to *change* the value of `self` to "B", "C", etc? — Dave Newton, Oct 22 '11 at 15:32

score 4 · Accepted Answer · answered Oct 22 '11 at 15:33

4

Just use the destructive methods already provided by String.

def nextval!
  case self
  when "A"
    replace("B")
  when "B"
    replace("C")
  # etc
  end
end

answered Oct 22 '11 at 15:33

d11wtq

Wow it works. :) Thanks. +1 and accept(have to wait 4 min..). – nothing-special-here Oct 22 '11 at 15:38

score 1 · Answer 2 · answered Oct 22 '11 at 15:34

1

There is such method - String#next!

a = "foo"
a.next! # => "fop"
puts a  # => "fop"

answered Oct 22 '11 at 15:34

WarHog

I know. But I writed that code just for example. I want to add more complex method. – nothing-special-here Oct 22 '11 at 15:36
For 'destructive' method you should add exclamation mark at the end of name method (that's just a convention) and to make some changes to 'self'. But not all methods with ! at the end are the destructive one, i.e. 'at_exit!', so that mark usually indicates that the method should be used cautiously. – WarHog Oct 22 '11 at 15:45

2 Answers2