From: Florian Gross <flgr@...>
Date: 2005-01-20T08:01:01+09:00
Subject: Re: value by reference

why the lucky stiff wrote:

> Florian Gross (flgr@ccan.de) wrote:
> 
>>>So far, the cons are two:
>>>
>>>1. The current model doesn't support it. 
>>>2. The performance would be poor: 
>>>
>>>[...] but maybe that statement ("ruby doesn't
>>>work that way") is enough to stop any further improvement.
>>
>>I disagree. I think there are some core principles of Ruby that make it 
>>Ruby. These should not change, especially not if there are no good 
>>sample situations that would require the change to work correctly.
> 
> Disagreement here as well.  I've needed Object#become quite a bit in my
> travels and I think Ruby could support it without incurring cost.  It's
> as simple as a memcpy of an RStruct.

Actually, it isn't. Have a look at the evil-ruby project. There is a lot 
of cases that can lead to segfaults and endless loops with such a naive 
implementation.

It's especially important that the RStructs are compatible meaning you 
can not use it generally anyway.

I don't quite see how the two things (introducing variable-by-ref 
semantics) and Object#become are related. Plus I was sort of arguing 
against the stuff I quoted, e.g. not wanting to implement a feature in 
the general case.

> I only have one use case:  I'm building a complex Ruby object, when I find
> a point of recursion or transformation which requires me to retrace my 
> steps and replace a node farther back in the tree.

If it's a tree then there will usually only be one place that refers to 
your Object. It ought to be possible to replace it even without #become.

As said: Note that I'm not against toying around with ideas or 
implementing well tested ideas that match up with the languages core 
philosophy without introducing too much new complexity.