From: John Maclean <info@...>
Date: 2006-02-03T03:29:54+09:00
Subject: Re: Chomping and stomping

Chaps,

Thanks for those speedy replies 
Following on from 

#thanks to you guyson the list for clearing this up
jayeola@tp20$ cat bin/acid/classes/testing/testchomp.rb
#!/usr/bin/ruby -w
def chomper
  xx = gets.chomp  
  until (xx= gets.chomp) == "qq"
    puts "hit me with a squirell!"
  end
  xx
end


chomper
# ^^ the above works. :)

# This is supposed to do the same as the above but write to a file...

here's version 1
#!/usr/bin/ruby -w

def  testwrite 
  puts "hit me with a squirell!" 
  until $_ =="qq" 
    gets.chomp! 
      if $_ != "qq"
        File.open("testfile", "a") { |file| file.write($_) } 
end 
end
end
 testwrite

here's version 1

jayeola@tp20$ cat bin/acid/classes/testing/write_file2.rb 
#!/usr/bin/ruby -w

def testwrite
  xx = gets.chomp
  until (xx.gets.chomp) == "qq"
    puts "hit me with a squirell!"
    File.open("testfile", "a") { |file| file.write(xx) }
  end
end

testwrite





On Fri, 3 Feb 2006 02:16:11 +0900
Jacob Fugal <lukfugl@gmail.com> wrote:

> On 2/2/06, John Maclean <info@jayeola.org> wrote:
> > #!/usr/bin/ruby -w
> > def chomper
> >   xx = gets.chomp!
> >   until $_ == "qq"
> >     puts "hit me with a squirell!"
> >     xx = gets.chomp!
> >     xx
> >   end
> > end
> >
> > chomper
> >
> > # this works but surely there must be a way to incoporate a variable
> > in there?
> >
> > #!/usr/bin/ruby -w
> > def chomper
> >   xx = gets.chomp!
> >   until xx == "qq"
> >     puts "hit me with a squirell!"
> >     xx
> >   end
> > end
> >
> > #this don't work.
> 
> String#chomp! is a "destructive" operation. This means that it acts in
> place on its receiver and, in this case, returns nil. So what's
> happening here is that Kernel#gets creates a String object, chomp! is
> sent to that object, the object is modified in place and nil returned.
> That's why xx is nil. As you discovered in your first example, the
> String object returned by Kernel#gets is stored in $_. Accessing it
> this way isn't a bset practice however.
> 
> What you probably want instead is to use the non-destructive twin (the
> Good Twin) of String#chomp!, namely String#chomp. Notice the lack of
> the bang (!). The bang is generally (but not always) an indicator that
> the method is destructive. String#chomp creates a chomped copy of it's
> receiver and returns it. Replacing chomp! with chomp it should work:
> 
>   #!/usr/bin/ruby -w
>   def chomper
>     xx = gets.chomp
>     until xx == "qq"
>       puts "hit me with a squirell!"
>       xx
>     end
>   end
> 
>   puts chomper
> 
> Jacob Fugal
> 
> 
> 


-- 
John Maclean
MSc (DIC)
07739 171 531