thinkings on shallow copy

[Steven Taschuk]

Quoth Kendear:
> i was just looking at docstrings and saw the one
> for copy.__doc__ regarding copy.copy():
> 
>  > - A shallow copy constructs a new compound object and then (to the
>  >   extent possible) inserts *the same objects* into in that the
>  >   original contains.
> 
> I wonder if it is actually to insert *the same object references*
> into the new compound object...

Sort of.  Better: "inserts references to the same objects".

(Saying that the references are the same suggests, erroneously,
that changing one reference would change the other:
    a = [1, 2, 3]
    b = copy.copy(a)
    a[0] = 'q'
    print b[0]   # does not print 'q'
)

The notion of references is so pervasive in Python that these docs
shouldn't need to emphasize it, imo.

  [...]
> so shallow copy constructs a new compound object
> and copies the references in the source compound
> object to the new compound object, is that correct?

Correct.

-- 
Steven Taschuk             "[W]e must be very careful when we give advice
staschuk at telusplanet.net    to younger people: sometimes they follow it!"
                             -- "The Humble Programmer", Edsger Dijkstra