From: dblack@...
Date: 2006-12-14T07:32:10+09:00
Subject: Re: Pointers and References?

Hi --

On Thu, 14 Dec 2006, Eero Saynatkari wrote:

> On 2006.12.14 05:20, dblack@wobblini.net wrote:
>> Hi --
>>
>> All of this means that if you do something to the arguments in a
>> method, the changes are permanent in the original object:
>>
>>   def add_element(array)
>>     array.push("new element!")
>>   end
>>
>>   a = [1,2,3]
>>   add_element(a)
>>   p a
>
> Just to make it clearer: anything destructive or mutating you do to the
> object inside the method will propagate to the original object.

And yet clearer: the object inside the method IS the original object
:-)

>> Some values are immediate; i.e., when you assign a variable to them,
>> they get stored directly and not via a reference: integers, true,
>> false, nil, and symbols (and any I've forgotten).  Hence the "almost
>> everything" above.
>
> I think this can just be considered to be an implementation detail,
> frankly. Fixnums etc. just do not have any destructive methods that
> one could employ inside a method.

The immediate-value thing does play a role in some language-design
things, though, particularly the absence of x++ on the grounds that
doing 1++ doesn't make any sense and, given x = 1, x *is* 1.


David

-- 
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