From: Nikolai Weibull <now@...>
Date: 2011-10-14T23:05:59+09:00
Subject: Re: What’s the best way of checking if an argument has been given or not?

On Fri, Oct 14, 2011 at 15:51, Chris Hulan <chris.hulan@gmail.com> wrote:
> You could do it as a wrapper:
>
> def foo_argchek *args
>  if args.len == 0
>    "no args given"
>  else
>    real_foo(*args)
>  end
> end
>
> def real_foo(arg1, arg2)
>  #do stuff
> end

How is this a solution (to anything)?

One can, of course, use define_method (in 1.9), but it’s not ideal, as
you can’t pass a block to A#a in that case.

class A
  missing = Object.new
  define_method :a do |b = missing|
    if b == missing
      puts 'no argument given'
    else
      puts b
    end
  end
end

A.new.a
A.new.a 1