From: Eric Hodel <drbrain@...7.net>
Date: 2005-10-21T05:05:48+09:00
Subject: Re: DbC, const and freeze.


On Oct 20, 2005, at 7:01 AM, Ryan Leavengood wrote:

> On 10/19/05, John Carter <john.carter@tait.co.nz> wrote:
>
>>
>> For example, look at this hole...
>> irb
>> irb(main):001:0> a = [[1,2],[3,4]]
>> => [[1, 2], [3, 4]]
>> irb(main):002:0> a.freeze
>> => [[1, 2], [3, 4]]
>> irb(main):003:0> a << [9]
>> RuntimeError: can't modify frozen array
>>         from (irb):3:in `<<'
>>         from (irb):3
>>         from :0
>> irb(main):004:0> a[0]<<1
>> => [1, 2, 1]
>> irb(main):005:0> a
>> => [[1, 2, 1], [3, 4]]
>> irb(main):006:0>
>>
>> Even though "a" was frozen, I still could modify the things "a"  
>> contained.
>>
>
> Fair enough. How about this:
>
> class Object
>   def deep_freeze
>     self.freeze
>     if self.respond_to? :each
>       self.each do |i|
>         i.deep_freeze
>       end
>     end
>   end
> end

Does not freeze instance variables.

instance_variables.each do |ivar|
   instance_variable_get(ivar).deep_freeze
end

I think.

-- 
Eric Hodel - drbrain@segment7.net - http://segment7.net
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