From: Jos Backus <jos@...>
Date: 2007-03-22T12:26:01+09:00
Subject: Re: Ruby Method Signatures (was Re: Multiton in standard library)

On Thu, Mar 22, 2007 at 10:52:56AM +0900, TRANS wrote:
> On 3/21/07, Jos Backus <jos@catnook.com> wrote:
> >On 3/19/07, TRANS <transfire@gmail.com> wrote:
[snip]
> I'm a little confused, What's output of this?
 
It prints a suitably indented execution trace showing caller and
arguments/return values.

> This maybe completely aside, but the above reminds me that with
> 'this', there could be:
> 
>  def(a,b)
>    Trace.begin(*this.arguments)
>  end
> 
> Basically args irregardless of the the actual signature.
> 
> As for the signature, it would have to be a special class of object
> that has the qualities of Ruby's arguments -- the ordered list, the
> default params and etc. With that object a few things could be
> queried, such as arity, maybe a list of parameter names, whether it
> has a * parameter or a &block parameter, etc. Importantly it could
> output a string representation or the args (whether with the original
> names or not). Eg.
> 
>  def a(x,y)
>    this.signature.to_s  #=>  "x,y" -or- "a1,a2"
> 
> A bonus would be to use the arguments in place of actual arguments
> when defining a method.
> 
>  def foo(x)
>  end
> 
>  def bar(*=method(:foo).signature)
>    p x   # or  p a1
>  end
> 
>  bar(1)  #=> 1
> 
> The *= is needed b/c there has to a special way to indicate that.
> 
> T.

This looks neat. But I'm worried about the potential overhead this could
introduce.

-- 
Jos Backus
jos at catnook.com