Why is this legal?

[Michael George Lerner]

"Delaney, Timothy C (Timothy)" <tdelaney at avaya.com> wrote:
> Michael George Lerner write:

>>     cluster = [(c.resi,c) for c in cluster] # decorate
>>     cluster.sort()                          # sort
>>     cluster = [c for (c.resi,c) in cluster] # undecorate
>> 
>> That last line actually assigns c.resi for each c in cluster.

> Normally the best way to write the above is:

>      cluster = [(c.resi,c) for c in cluster] # decorate
>      cluster.sort()                          # sort
>      cluster = [c[-1] for c in cluster]      # undecorate

> It's shorter, clearer, works no matter how many elements are in the
> decoration, and doesn't have the danger of your version.

Good points.  Thanks.

I'll re-train myself to write it that way.

Heck, maybe I'll even download Python 2.4 so I can say
cluster.sort(key=lambda c: c.resi)

-michael


> Tim Delaney