From: Charles Mills <cmills@...>
Date: 2004-11-06T02:54:51+09:00
Subject: Re: value provided for argument with default value - how to check inside method?

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.

-Charlie