From: Daniel DeLorme <dan-ml@...42.com>
Date: 2007-05-30T07:26:56+09:00
Subject: Re: True arity

Robert Dober wrote:
> On 5/29/07, Daniel DeLorme <dan-ml@dan42.com> wrote:
>> Is there a way to get the *maximum* number of arguments that a method
>> can receive? Method#arity only gives the lower bound...
> 
> I am afraid I fail to understand, what would you define as the maximum?
> 
> def a(a)...  I would say the maximum is 1 which is the arity
> def b(*b)   arity is -1 but what would the maximum of parameters be?
> def c(c,*d) arity = -2 but some question as above.
> 
> The question is, what would you like to achieve?

In the last 2 cases you give the maximum would be Infinity. But in a 
case like this:
   def foo(a, b=nil, c=nil)
the maximum would be 3 but arity only gives me -2 which means "this 
method has 1 required argument". If I invoke the method like:
   foo(*args)
I want to know for what size of args is this valid? It would be nice if 
arity returned a Range object (1..3)

Daniel