Question about idioms for clearing a list

bearophileHUGS at bearophileHUGS at
Tue Jan 31 22:47:55 CET 2006

Diez B. Roggisch:
> The reason is that l = [] just rebinds a new object (a list, but it could be
> anything) to a name, while l[:] = [] will alter the object _referred_ to by
> l. That is a HUGE difference!

In my programs I have seen that there is another practical difference
between version 1 and 3:
(1) mylist[:] = []
(3) mylist = []
If you create a big mylist again and again many times, the version 1
uses the memory more efficiently (probably less work for the garbage
collector), and the program can be (quite) faster (this is true in some
implementations different from CPython too).


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