From: Robert Klemme <bob.news@...>
Date: 2003-07-22T14:29:03+09:00
Subject: Re: Should String#strip take a parameter?


"Warren Brown" <wkb@airmail.net> schrieb im Newsbeitrag
news:000201c34fd3$22b24cb0$6449c4d1@warrenpc...
> All,
>
>     Several times I have run across the need to strip characters other
than
> whitespaces from the beginning and/or end of a string.  I have always
> accomplished this using String#sub (or String#gsub) and an appropriate
> pattern.  For example:
>
> price = field.sub(/^0+/,'')
> descr = field.gsub(/(^_+)|(_+$)/,'')

.... which is not too bad, isn't it?

>     It occurs to me that this would be a natural extension to the
> String#strip methods (1.8 now includes String#lstrip and String#rstrip as
> well as the "!" variations) by adding an optional String parameter to
them.
> The default value of the parameter would be nil to preserve backwards
> compatibility, but if the parameter was not nil, the functions would strip
> that string (or the string returned by that object's to_str method).
>
>     Example behavior:
>
> class String
>
>   def new_lstrip(str = nil)
>     return self.lstrip if str.nil?
>     self.sub(/^#{str}+/,'')
>   end

If you want to exactly match str you should use Regexp.quote for the
argument.  Otherwise I'd use a regexp directly and match it at the beginning
and at the end.  Maybe like this:

class String
  SPACES = /\s+/o

  def new_strip!(rx=SPACES)
    gsub!(rx) {|m| $`==""||$'=="" ? nil : m}
  end

  def new_strip(rx=SPACES)
    s=dup; s.new_strip! rx; s
  end

  def new_lstrip!(rx=SPACES)
    gsub!(rx) {|m| $`=="" ? nil : m}
  end

  def new_lstrip(rx=SPACES)
    s=dup; s.new_lstrip! rx; s
  end

  def new_rstrip!(rx=SPACES)
    gsub!(rx) {|m| $'=="" ? nil : m}
  end

  def new_rstrip(rx=SPACES)
    s=dup; s.new_rstrip! rx; s
  end
end

Regards

    Robert