On 5/15/09, Steven D'Aprano firstname.lastname@example.org wrote:
On Fri, 15 May 2009 08:26:30 pm Nick Coghlan wrote:
Steven D'Aprano wrote:
...inside the parameter list, &x would mean to delay evaluation ...
Marking the parameter name strikes me as wrong anyway - it's only the evaluation of the default argument which is special, not the parameter itself.
But it is the parameter that is special. The default object itself is not. Consider the function definition:
def f(x=, &y=):
(or any other syntax you prefer). The empty list you get as the default value for x is exactly the same as the empty list you get in y, in every way except for identity.
Logically, you're correct. But I think the ('&' ==> addressof) meme may have already grown too strong. What it suggests to me is that normally you *would* create a new list, but the ampersand says not to in just this rare case.