[Python-ideas] Default arguments in Python - the return - running out of ideas but...

[Terry Reedy]

Bruce Leban wrote:
> Here's what I'd like:
> 
> def myfunc(a, b, c = *lambda: expression):
>   stuff
> 
> The use of the lambda keyword here makes the scope of any variables in 
> the expression clear. The use of the prefix * makes the syntax invalid 
> today, suggests dereferencing and doesn't hide the overhead. This is 
> equivalent to:

There is a proposal, which I thought was accepted in principle, to make 
'* seq' valid generally, not just in arg-lists. to mean 'unpack the 
sequence'. * (lambda:1,2)() would then be valid, and without the call, 
would be a runtime, not syntax error.

Other than that ;0(, it would be an interesting idea.

> __unset = object()
> __default = lambda: expression
> def mfunc(a, b, c = __unset):
>   if c == __unset:
>     c = __default()
>   stuff

tjr