From: Charles Mills <cmills@...>
Date: 2004-11-06T03:20:12+09:00
Subject: Re: value provided for argument with default value - how to check inside method?


On Nov 5, 2004, at 9:54 AM, Charles Mills wrote:

> On Nov 4, 2004, at 8:03 PM, itsme213 wrote:
>
>> Is there an equivalent of block_given? to check if the caller 
>> provided a
>> value to an argument that had a default value?
>>
>> Or do I have to use some sentinel value?
>
> I remember Nobu had a solution for this... I can't seem to find it 
> though.  I think it was something like this:
>
> > def foo(x=(nil; a=true))
> > puts a
> > end
> => nil
> > foo()
> true
> => nil
> > foo('value')
> nil
> => nil
>
> You can replace nil with the default value you want.

> a will be set to true if a value is passed in, nil otherwise.
                                     -----
I meant "unless a value is passed in"