From: Daniel DeLorme <dan-ml@...42.com>
Date: 2008-10-02T14:47:20+09:00
Subject: Re: ruby1.9 block scope

Daniel DeLorme wrote:
> Ok, I now see that it is indeed O(n^2) complex. But you *already* have 
> to do that for large scopes; you have to consider every variable that 
> previously appeared in the scope, and that's O(n^2). The new rule would 
> make it 2*O(n^2) [which, in math speak, is still O(n^2)]. But this is 
> only a problem if n is very large; if you really have a scope that long 
> then I dare say that you already have a problem and some refactoring is 
> in order. Whatever happened to "no more than 10-20 lines per method" ?

Sorry, I didn't think this through enough.

The new rule would not change the current rule that variables defined at 
L are not considered as variables at all at lines L-n. So under the new 
rule, code would have mathematically the *same* complexity but 
practically it might be more tricky:

   define_method :foo do
     #say, 20 lines of code
   end
   foobar

under new rules, you'd have to backtrack until the top of the scope to 
see if "foobar" is a variable or not.

under old rules, you'd have to backtrack until the top of the scope to 
see if "foobar" is a variable or not, while taking into account that 
variables defined in a sub-scope are self-contained, which means that 
you can skip large sections of indented code.

I hope I got it right this time.

--
Daniel