From: Benoit Daloze <redmine@...>
Date: 2011-07-22T21:58:36+09:00
Subject: [ruby-core:38396] [Ruby 1.9 - Bug #5077] method_missing throws NoMemoryError after inheriting from BasicObject


Issue #5077 has been updated by Benoit Daloze.


Farruco Sanjurjo wrote:
> If a class inherits from BasicObject and then overwrites method_missing like this:
> 
> class A < BasicObject
>   def method_missing(*a)
>      puts "#{a}"
>   end
> end
> 
> And we try it:
> 
> A.new.fooooo
> 
> 
> The interpreter enters what looks like a loop and then crashes with this trace (in irb):

method_missing is called indefinitely recursively because "puts" is not a method in BasicObject.

Only methods available in BasicObject are:
BasicObject.instance_methods # => [:==, :equal?, :!, :!=, :instance_eval, :instance_exec, :__send__]

"puts" is usually provided by Kernel#puts. But Kernel is not included in BasicObject.
You could solve this two ways:
* use "::Kernel::puts" instead of "puts" (the documentation about the first :: is being discussed in Bug #5067)
* include Kernel into your class A

----------------------------------------
Bug #5077: method_missing throws NoMemoryError after inheriting from BasicObject
http://redmine.ruby-lang.org/issues/5077

Author: Farruco Sanjurjo
Status: Open
Priority: High
Assignee: 
Category: 
Target version: 1.9.2
ruby -v: ruby 1.9.2p290 (2011-07-09 revision 32478) [x86_64-linux]


If a class inherits from BasicObject and then overwrites method_missing like this:

class A < BasicObject
  def method_missing(*a)
     puts "#{a}"
  end
end

And we try it:

A.new.fooooo


The interpreter enters what looks like a loop and then crashes with this trace (in irb):

NoMemoryError: failed to allocate memory
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'
	from (irb):3:in `method_missing'

If we create the same class with the same method_missing but without inheriting from BasicObject it works right.


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