On 05/07/2015 04:54 PM, Jim Mooney Py3.4.3winXP wrote:
On 7 May 2015 at 13:03, Emile van Sebille <em...@fenx.com> wrote:Compare to: def testid(K=1000000): K += 10 return 'the ID is', id(K), KAh, thanks. I forgot small integers are saved in a table. I was looking at a demo that pointers to defaults in function parameters are persistent.
Python doesn't have pointers, and nothing here is persistent. Persistence refers to a value surviving multiple invocations of a program.
It used lists so I tried ints. Although I realized persistence also works for dicts ;') def testid(newitem, K={}): K[newitem] = newitem + 'item' return 'the ID is', id(K), Ktestid('bonk')('the ID is', 18263656, {'bonk': 'bonkitem'})testid('clonk')('the ID is', 18263656, {'bonk': 'bonkitem', 'clonk': 'clonkitem'})testid('spam')('the ID is', 18263656, {'bonk': 'bonkitem', 'clonk': 'clonkitem', 'spam': 'spamitem'})
The object is not immutable, so it can change. Therefore the += does an in-place change, and you keep the same id.
-- DaveA _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
