From: Daniel Brockman <daniel@...>
Date: 2005-07-20T00:37:16+09:00
Subject: Re: [RCR] nil for unassigned keys

Hi Pit,

Thank you for your comments.

>> This would also reasonably mean that mixing optional and
>> mandatory arguments would become allowed:
>>
>>    def bar(a, b=nil, c, d=nil, e) ... end
>>
>>    bar 1                # ArgumentError
>>    bar 1, 2             # ArgumentError
>>    bar 1, 2, 3          # a=1, b=nil, c=2, d=nil, e=3
>>    bar 1, 2, 3, 4       # a=1, b=2,   c=3, d=nil, e=4
>>    bar 1, 2, 3, 4, 5    # a=1, b=2,   c=3, d=4,   e=5
>
> I don't like this. It is hard to see which value is put
> into which parameter. Picking some arguments from the left
> and from the right and stuffing the rest in the splatted
> parameter is easier to grasp, at least for me.

Then what about this?

   def baz(a, b=nil, c) ... end

Isn't that just as easy to grasp as this?

   def baz(a, *b, c) ... end

> I think the chances to get the RCR accepted are higher if
> you drop this feature.

You may be right.  But I think restricting this to “only if
there's a splat argument somewhere!” is pretty arbitrary.

If you wanted the semantics of this,

   def baz(a, b=nil, c) ... end

you'd have to write it like this,

   def baz(a, *dummy, b=nil, c)
     dummy.empty? or raise ArgumentError
     ... end

which seems pretty annoying-for-no-reason.

-- 
Daniel Brockman <daniel@brockman.se>

    So really, we all have to ask ourselves:
    Am I waiting for RMS to do this?   --TTN.