[Python-Dev] Slice as a copy... by design?

[Gary Herron]

Facundo Batista wrote:
> Hi!
>
> A thread in PyAr raised the question that, considering that strings
> are immutable, why a slice of a string is a copy and not a reference
> to a part of that string.
>
> I couldn't answer why, so I'm asking here...Is it because the
> reference counting will be complicated? Is it because it'd be
> inefficient in other way? It's something else? Or is something that
> could be done... but is not done yet?
>
> Thank you very much!
>
>   

In fact, a slice is *not* always a copy!  In at least some (simple) 
cases, a slice references the original string:

 >>> s = 'abc'
 >>> t = s[:]
 >>> s is t
True
 >>> id(s)
3081872000L
 >>> id(t)
3081872000L

Gary Herron