Bug #12535: are there 2 sleep methods defined?

• Status: Rejected
• Assignee: -
• Target version: -
• Backport: 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN

[chucke (Tiago Cardoso)]

I'm updating this gem which "patches" the sleep method to use prepend, as I wanted to drop support to ruby < 2.0 . (previous implementation was using alias method chain like solution)

So I came across this funny behaviour:

module AlternativeSleep
  def sleep(*)
    puts "going to sleep now..."
    super
  end
end

class << self
  prepend AlternativeSleep
end
class << Kernel
  prepend AlternativeSleep
end

puts "these are the locations..."

puts Kernel.method(:sleep)
puts method(:sleep)

puts "now to work. if you see the going to sleep message only once, there's your bug"

Kernel.sleep 1
sleep 1

In order to make sleep work in both cases, I have to do those 2 prepends. Try to comment one of them, and you'll see that one of them will always work.

I'm led to believe that sleep method has two implementations, although that doesn't seem to make sense. Could you provide with some insight?

When I was using the alias-method-chain example, I was including in the main object, as main#sleep somehow seemed to land in Kernel.sleep (?) .

[nobu (Nobuyoshi Nakada)]

• Description updated (diff)
• Status changed from Open to Rejected

No.
You are prepending the method on 2 different objects, main and Kernel.

[chucke (Tiago Cardoso)]

Yes I am. My point being, I can't overwrite the sleep method only in one place, as it is apparently defined in two different objects. Why not just one?

The main.timeout method (which has been already deprecated) at least redirected to Timeout.timeout, which meant I only had to patch that one.

[chucke (Tiago Cardoso)]

• Assignee set to nobu (Nobuyoshi Nakada)

@nobu (Nobuyoshi Nakada), can you check my last comment? I think this is a valid concern, as in "the same method defined in two objects".

[nobu (Nobuyoshi Nakada)]

• Assignee deleted (nobu (Nobuyoshi Nakada))

If you want to overwrite the method globally, prepend the module to Kernel instead of the singleton class of it.

[chucke (Tiago Cardoso)]

I've just tried that, it's not delivering the expected result. Try this out:

module AlternativeSleep           
  def sleep(*)                    
    puts "going to sleep now..."  
    super                         
  end                             
end                               
                                  
Kernel.prepend AlternativeSleep   
                                  
# none of these work
Kernel.sleep 1                    
sleep 1                           

I guess it's because Kernel is a module already.