__init__ keyword param for sub-class?

[Bernhard Herzog]

"Fred L. Drake, Jr." <fdrake at acm.org> writes:

>   I think it would be nice to have a way to specify that an argument
> *must* be given as a keyword parameter, and have it never be filled in 
> from positional parameters.  Perhaps something lispish:
> 
>     def __init__(self, *posArgs, **keyArgs, :myoption):
>         self.__myoption = myoption
>         return Pmw.ScrolledText.__init__(self, *posArgs, **keyArgs)

I agree that this would be a very useful feature, although I think

    def __init__(self, *posArgs, myoption=, **keyArgs):

would be a more pythonic notation and the order of arguments makes more
sense to me. After all, the myoption argument is to be bound to the
local variable myoption and **keyArgs collects all remaining keyword
args.

In my example, myoption must be provided because it has no default value
and it must be a keyword argument. It should also be possible to assign
a default value with the obvious notation:

    def __init__(self, *posArgs, myoption=1, **keyArgs):

In this case, myoption may be given as an argument or not, but if it's
given it must be a keyword arg.

Hmm, my post almost sounds like a proposal...

-- 
Bernhard Herzog   | Sketch, a drawing program for Unix
herzog at online.de  | http://sketch.sourceforge.net/