[Python-Dev] List copy and clear (was Re: Inconsistent API for sets.Set and build-in set)

[Nicolas Fleury]

Raymond Hettinger wrote:
> Use copy.copy() for generic copying -- it works across a wide range of
> objects.  Alternatively, use the constructor as generic way to make
> duplicates:
> 
>    dup = set(s)
>    dup = list(l)
>    dup = dict(d)
>    dup = tuple(t)     # note, the duplicate is original object here :-)

I know all this, but why then is there a copy method for sets and 
dictionaries?  What justification is valid for sets and dictionaries 
that doesn't apply to lists?

Regards,
Nicolas