[Python-ideas] function defaults and an empty() builtin

[Terry Reedy]

On 5/20/2011 3:10 PM, Bruce Leban wrote:
> It seems to me that a better way of doing this is:
>
>      def func(optional_list=[])
>          optional_list = freeze(optional_list)

If a function only needs a read-only sequence, it should not require or 
to said to require a list. "def func(optional_seq = ()):". If it only 
iterates through an input collection, it should only require an 
iterable: "def func(optional_iter=()): it = iter(optional_iter)". If you 
are paranoid and want the function to raise on any attempt to do much of 
anything with the input, replace '()' with 'iter()'.

-- 
Terry Jan Reedy