No swap function in Python?

Thomas Wouters thomas at
Wed May 30 17:33:28 CEST 2001

On Wed, May 30, 2001 at 04:57:41PM +0200, Bolton, Gawain [ADC:4808:EXCH] wrote:

> There doesn't seem to be a "swap" function in Python two swap the values
> of two variables.   I was wondering why this is.

Because it isn't necessary.

> Unfortunately writing a generic swap function swap(a,b) with no return
> type in Python doesn't work with immutable arguments (like strings) of
> course.  Which made me think that a swap could be done like this:

> (a,b) = (b,a)

> But I'm not completely convinced doing this is safe.

It is.

> In tests I've done it works, but I'm not sure whether this works in all
> cases with all types...  Finally, if the behaviour is guaranteed, is this
> an efficient way of doing a swap?


Thomas Wouters <thomas at>

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