From: matz@... (Yukihiro Matsumoto)
Date: 2003-02-21T17:22:50+09:00
Subject: Re: proc {} vs. Method#to_proc

Hi,

In message "Re: proc {} vs. Method#to_proc"
    on 03/02/21, "Robert Klemme" <bob.news@gmx.net> writes:

|> -1 means 0 or more args, -2 means 1 or more args, etc
|
|I know that, sorry if I wasn't clear enough. What bugs me is the fact that
|the block with a single argument has negative arity, indicating that there
|can be more arguments. Why then doesn't the block with two arguments have
|arity -2, too?  Or otherwise, why doesn't the block with |a| have arity 1?

  proc{|a|...}.call(1,2,3)

works like

  a = 1,2,3   # a = [1,2,3]

so that it takes arbitrary number of argument (thus arity = -1).  If
you want to receive one argument and only one, you have to do |a,|
which works like

  a, = 1,2,3  # a = 1

							matz.