From: Brian Candler <b.candler@...>
Date: 2010-11-11T23:59:09+09:00
Subject: Re: what's an object?

Ammar Ali wrote in post #960710:
>> No variable ever *is* an object in Ruby.  Variables *reference* objects!
>
> Now that's a different, or at least clearer, statement. And it fits
> with what I know.

Yes. It's important when you compare "pass by value" or "pass by 
reference" in other languages. In ruby, everything is "pass by value", 
and each value is a reference to an object - even integers.

IMO this is a *huge* logical simplification over languages like perl 
(scalar? array? array ref? list? hash? hash ref? filehandle? typeglob? 
subroutine? Deal with them all differently)

In ruby, a local variable is not an object, and as such you can never 
obtain a "reference" to it.

def foo(x)
  x << " world"
end

a = "hello"
foo(a)

a is passed by value, so the method call foo(a) can never affect the 
value of a - it must remain pointing to the same object after the call. 
However, if the object is mutable, it can cause it to change state 
(using the << method in the example above)

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