From: Andrew Grimm <andrew.j.grimm@...>
Date: 2012-05-12T08:07:21+09:00
Subject: Re: Why do you think of NilClass#to_proc?

On Sat, May 12, 2012 at 6:42 AM, Jan E. <lists@ruby-forum.com> wrote:
> Hi,
>
> Thomas Sawyer wrote in post #1060469:
>> I have two minds about using a NilClass#to_proc
>>
>>     class NilClass
>>       def to_proc
>>         Proc.new{ |*a| a }
>>       end
>>     end
>>
>> Or
>>
>>     class NilClass
>>       def to_proc
>>         Proc.new{ nil }
>>       end
>>     end
>>
>> Which makes the most sense?
>
> The second solution seems more intuitive to me, since it's a kind of
> "empty proc": all parameters are discarded and the proc returns nil.
>
> But like Bartosz already said: What's the use case for this feature?
>

I had a look at nil last year
http://stackoverflow.com/questions/7410748/how-does-foonil-behave-differently-than-foonot-a-proc

[1, 2, 3].each(&nil)
doesn't cause any errors, it just returns an enumerator.

Passing in &nil to a method causes block_given to return false:

def block_given_tester
  if block_given?
    puts "Block given"
  else
    puts "Block not given"
  end
end

block_given_tester(&nil) # => Block not given

Even when I create NilClass#to_proc, it still says block_given? is
false, unless I explicitly call nil.to_proc:

class NilClass
  def to_proc
    Proc.new{ nil }
  end
end
block_given_tester(&nil) # => Block not given
block_given_tester(&nil.to_proc) # => Block given

I'd try to avoid monkeypatching NilClass if possible.

Andrew