From: Mohammad Khan <mkhan@...>
Date: 2004-11-13T04:35:28+09:00
Subject: Re: true? & false?

On Fri, 2004-11-12 at 13:54, Michael DeHaan wrote:
> "In ruby there have many methods that names end with '!' like, collect!,
> compact!. I was so used to that '!' means its return the object after
> 'affect' and without '!' return the part of the object that was
> affected."
> 
> The exclamation actually means the operation is destructive and
> forever changes the contents of the calling object.   It doesn't have
> anything to do with the return codes.   It's a very nice convention.
> 
> Here is a good example: 
> http://www.rubycentral.com/book/ref_c_string.html#String.chomp
> 
> In this case, both examples would return the same string, but one
> would change the string it was called against.
> 

Thanks for your nice explanation on exclamatory sign.
And Sorry for my poor English.

See the example below, I was confused with Array#delete! and
Array#delete. Bottom line is, if there have something unfamiliar, I will
have to learn it to make it familiar. There is no other way around.

[mkhan@localhost bin]$ irb
irb(main):001:0> arr = [1, 2, 2, 2, 3, 4]
=> [1, 2, 2, 2, 3, 4]
irb(main):002:0> str = "string"
=> "string"
irb(main):004:0> p arr
[1, 2, 2, 2, 3, 4]
=> nil
irb(main):005:0> p str
"string"
=> nil
irb(main):006:0> arr.delete(2)
=> 2
irb(main):008:0> str.delete("r")
=> "sting"
irb(main):009:0> p arr
[1, 3, 4]
=> nil
irb(main):010:0> p str
"string"
=> nil
irb(main):011:0> str.delete!("r")
=> "sting"
irb(main):012:0> arr.delete!(2)
NoMethodError: undefined method `delete!' for [1, 3, 4]:Array
        from (irb):12
irb(main):013:0> p str
"sting"
=> nil
irb(main):014:0> p arr
[1, 3, 4]
=> nil
irb(main):015:0>

Mohammad
-- 

[mkhan@localhost local]$ make love
make: *** No rule to make target `love'.  Stop.