No swap function in Python?

[Gawain Bolton]

Nick Perkins wrote:

> "(a,b) = (b,a)" compiles to (approximately):
> >
> >     LOAD_FAST b
> >     LOAD_FAST a
> >     BUILD_TUPLE 2
> >     UNPACK_TUPLE 2
> >     STORE_FAST a
> >     STORE_FAST b
> >
> > It's easy to see how you can use the runtime stack without going through
> the
> > BUILD/UNPACK pair:
> >
> >     LOAD_FAST b
> >     LOAD_FAST a
> >     STORE_FAST b
> >     STORE_FAST a
> >
> > Any peephole optimizer can do this for you... ;-)
> >
> > Skip
>
> ..that looks a lot faster than the 'normal' way!
> (maybe there should be a built-in operator or something to do exactly that)
>

Firstly, thanks to everyone for their replies to this "trivial" question!

This is why I think it might be an idea to have a "swap" function in Python.
Besides making for more readable code - ok ok, I have not done a survey and
have no statistical or theoretical data to support this claim but let's
pretend humans understand words more readily than symbolic notation - a swap
function could generate the optimized code without any need for peephole
optimization.

Furthermore, as Aahz Maruch alludes to in another follow-up post, an "atomic"
swap might also be useful when writing multi-threaded applications.

That's my 2 Euro cents worth (which admittedly is not a lot!).


Gawain

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