From: Robert Klemme <shortcutter@...>
Date: 2008-10-30T01:54:30+09:00
Subject: Re: Bug or not a bug? array*=int

On 29.10.2008 17:26, Kyle Schmitt wrote:
> Ahh.
> And upon not being lazy and looking at the C, I see this...
> ary2 = ary_new(rb_obj_class(ary), len);
> 
> Which I'm guessing is equivalent to this in ruby (which I already knew
> would return the same array len times)
> ary2=Array.new(ary,len)
> 
> Any chance the document maintainer could slip the word "shallow" into
> the description of array*?

Dunno.  But all (or almost all) copies (e.g. dup, clone, Enumerable#map, 
Enumerable#select) do shallow copying only.  So shallow is the rule and 
not particularly exceptional - as it is also more efficient and deep 
copy is more complex (i.e. deciding when to create a new object or just 
copy the reference).  There are quite a few discussions of this topic in 
the archives...

For deep copies the idiom probably most often used is

copy = Marshal.load(Marshal.dump(obj))

Kind regards

	robert