From: Chris Thiel <ccthiel@...>
Date: 2007-07-26T03:50:52+09:00
Subject: Re: Question - Passing parameters by reference

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On 7/25/07, dblack@wobblini.net <dblack@wobblini.net> wrote:
>
> Hi --
>
> On Thu, 26 Jul 2007, Chris Thiel wrote:
>
> > What if the method is returning something else already and you don't
> want
> > to have to return the changed value? How do you pass in a variable to a
> > method and have the change stick when it exists the method in ruby?
>
> You can change an object:
>
>    def change_me(str)
>      str.upcase!
>    end
>
>    s = "abc"
>    change_me(str)
>    puts s          # ABC
>
> But you can't change the bindings.  In the example, I've got s and str
> both containing references to the same string.  But the names of the
> identifiers themselves, s and str, are solely the business of their
> local scopes, which are different as between the method body and the
> calling context.
>
>
> David
>
> --
> * Books:
>    RAILS ROUTING (new! http://www.awprofessional.com/title/0321509242)
>    RUBY FOR RAILS (http://www.manning.com/black)
> * Ruby/Rails training
>      & consulting:  Ruby Power and Light, LLC (http://www.rubypal.com)
>
> I'm talking in a case like this:
def add_one(number)
number+=1
end
n = 1
add_one(n)

While the method returns 2, the value of n when the method is done is still
one.

Or with strings
def add_bar(st)
st + "bar"
end

s = "foo"
add_bar(s)

Same thing. The method returns foobar, but the value of s is unchaged.
Is there a way to change the values of these variables from within the
method and have the values remain changed when the method has exited?

Chris

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