On 05/07/2015 07:51 PM, Dave Angel wrote:
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), K
Ah, 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.
I think the term you're looking for is "static lifetime". That object
will exist for the life of the program. The local variable name K is
bound to that object each time the function is called without an argument.
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), K
testid('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
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