On 31 Dec, 18:22, Arnaud Delobelle <[EMAIL PROTECTED]> wrote: > On Dec 31, 10:58 am, Odalrick <[EMAIL PROTECTED]> wrote: > > > On 30 Dec, 17:26, George Sakkis <[EMAIL PROTECTED]> wrote: > > > > On Dec 29, 9:14 pm, bukzor <[EMAIL PROTECTED]> wrote: > > > > > Here's the answer to the > > > > question:http://www.python.org/doc/faq/general/#why-are-default-values-shared-... > > > > > It looks like Guido disagrees with me, so the discussion is closed. > > > > Note that the FAQ mainly explains *what* happens, not *why* was this > > > decision taken. Although it shows an example where "this feature can > > > be useful", it's neither the only way to do it nor is memoization as > > > common as wanting fresh default arguments on every call. > > > I'm surprised noone has said anything about the why of default > > mutables. I think it is becasue it isn't easy to do it an other way. > > [...] > > There is an easy enough way: evaluate default values when the function > is called rather than when it is defined. This behaviour comes with > its own caveats as well I imagine, and it's not 'as easy' to implement > as the current one. >
Adding overhead to *all* function calls, even the ones without mutable defaults. That doesn't sound like an attractive tradeoff. > What's good about the current behaviour is that it is easy to reason > with (once you know what happens), even though you almost have to get > bitten once. But using this to have static variable is extremely ugly > IMHO. > > -- > Arnaud -- http://mail.python.org/mailman/listinfo/python-list
