From: Pit Capitain <pit@...>
Date: 2006-08-02T22:59:15+09:00
Subject: Re: I thought this was the one that worked?

Chad Perrin schrieb:
> In any case, this can happen in Ruby:
> 
>   class Foo
>     def bar
>       lambda { puts "quux" }
>     end
>   end
> 
>   foo = Foo.new
>   bar = foo.bar
> 
>   bar.call

Chad, I didn't carefully read all of this long thread because I've been 
offline for a couple of days. You don't have to answer to this mail, if 
it isn't relevant to you.

I had the impression that you think a block can't be called a closure if 
it doesn't reference any free variables from its context, just as the 
block in the example above. If I understand you correctly, then the 
following two blocks should be exactly the same, shouldn't they?

   blk1 = Foo.new.bar
   blk2 = Foo.new.bar

But they aren't the same, as can be seen from the following code:

   eval "self", blk1  # => #<Foo:0x2b851e0>
   eval "self", blk2  # => #<Foo:0x2b85138>

As you can see, each block remembers at least the value of "self", when 
it was created. You can get at this value even if the "self" object goes 
out of scope, as you can see from my code above. There's no explicit 
reference to the two instances of Foo. From this it follows (at least 
for me), that each block in Ruby is a closure.

Regards,
Pit