From: "Peña, Botp" <botp@...>
Date: 2007-07-20T18:12:26+09:00
Subject: Re: Is there a replacement for sub?

From: Michael W. Ryder [mailto:_mwryder@worldnet.att.net] 
# a = "a b c d e f"
# for i in 1..3
#    a = a.sub!(' ', '')
   ^^^^^
lose that

# end
# puts a  ==> returns 'abcd e f' which is correct.
# 
# But if I enter:
# 
# a = "a b c d e f"
# for i in 1..10
#    a = a.sub!(' ', '')
    ^^^^^
same. lose it.

# end
# puts a  ==> returns error.rb:3: private method `sub!' called for 
# nil:NilClass (NoMethodError, and a is now nil.

a.sub! will modify a. so, do NOT use a=a.sub!, it's NOT right.  just use plain a.sub!. ruby has already simplified it, do not make it simpler :)

eg,

C:\family\ruby>cat -n test.rb
     1  puts "---test 3 subs using for---"
     2  a = "a b c d e f"
     3  for i in 1..3
     4     a.sub!(' ', '')
     5  end
     6  puts a
     7
     8  puts "---test 10 subs using for---"
     9  a = "a b c d e f"
    10  for i in 1..10
    11     a.sub!(' ', '')
    12  end
    13  puts a
    14
    15
    16  puts "---test 3 subs using times---"
    17  a = "a b c d e f"
    18  3.times do
    19     a.sub!(' ', '')
    20  end
    21  puts a
    22
    23
    24  puts "---test 10 subs using times---"
    25  a = "a b c d e f"
    26  10.times do
    27     a.sub!(' ', '')
    28  end
    29  puts a

C:\family\ruby>ruby test.rb
---test 3 subs using for---
abcd e f
---test 10 subs using for---
abcdef
---test 3 subs using times---
abcd e f
---test 10 subs using times---
abcdef

C:\family\ruby>

is that clear enough?

kind regards -botp