On 2006.01.24 21:19, Gioele Barabucci wrote:
> Hi,
> 
> why does class_eval behave differently is you pass a string or a block to it?
> This simple test
> 
> | class A
> |   def test_str; p self.class.class_eval("@@v"); end
> |   def test_blk; p self.class.class_eval { @@v }; end
> | end
> | 
> | class B < A
> |   def initialize; @@v = "v.B"; end
> | end
> | 
> | B.new.test_str
> | B.new.test_blk
> 
> gives this (unexpected?) result
> 
> | $ ruby ./cv2.rb
> | "v.B"
> | ./cv2.rb:3:in `test_blk': uninitialized class variable @@v in A (NameError)
> |         from ./cv2.rb:3:in `class_eval'
> |         from ./cv2.rb:3:in `class_eval'
> |         from ./cv2.rb:3:in `test_blk'
> |         from ./cv2.rb:11

Reason for that is that all blocks are closures (they 'enclose' the
scope they were defined in). In this case, @@v is bound to the @@v
in class A at the time you create the block.

> Gioele <dev / gioelebarabucci.com>


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