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

[Terry Reedy]

MRAB wrote:

> There's the suggestion that Carl Johnson gave:
> 
>     def myfunc(a, b, c else []):
>         pass
> 
> or there's:
> 
>     def myfunc(a, b, c def []):
>         pass
> 
> where 'def' stands for 'default' (or "defaults to").

I had the idea of def f(c=:[]): where ':' is intended to invoke the idea 
of lambda, since the purpose is to turn the expression into a function 
that is automatically  called (which is why lambda alone is not enough). 
  So I would prefer c = def [] where def reads 'auto function defined 
by...'.

or c = lambda::[] where the extra ':' indicates that that the function 
is auto-called

or c = lambda():[], (now illegal), where () is intended to show that the 
default arg is the result of calling the function defined by the 
expression.  lambda:[]() (now legal) would mean to (uselessly) call the 
function immediately.

Thinking about it, I think those who want a syntax to indicate that the 
expression should be compiled into a function and called at runtime 
should build on the existing syntax (lambda...) for indicating that an 
expression should be compiled into a function, rather than inventing a 
replacement for that.

Terry Jan Reedy