# Freeze not freezing **URL:** \ **Category:** Ruby\ **Created:** [November 5, 2009, 3:06pm UTC](https://www.ruby-forum.com/t/freeze-not-freezing/178500 "2009-11-05T15:06:04Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![ralphshnelvar](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/e19adc/32.png) [@ralphshnelvar](https://www.ruby-forum.com/u/ralphshnelvar)\ **Post date:** [November 5, 2009, 3:06pm UTC](https://www.ruby-forum.com/t/freeze-not-freezing/178500/1 "2009-11-05T15:06:04Z")
Note that I am new to this list and to Ruby. Consider … irb(main):020:0\> c=[0,1] =\> [0, 1] irb(main):021:0\> c[0].freeze =\> 0 irb(main):022:0\> c[0]=2 =\> 2 irb(main):023:0\> c =\> [2, 1] irb(main):024:0\> Similarly … irb(main):029:0\> f=1 =\> 1 irb(main):030:0\> f.freeze =\> 1 irb(main):031:0\> f=2 =\> 2 It took a few moments for me to scratch my head and then I thought that the reason that there was no message when c[0] or f changed was that c[0] is not an object but a reference to an object (the number 2). So I searched the archives and it appears taht my reasoning is correct. I think. there was the suggestion to make f a constant, F. Yes, that generates a warning … but it is not what I want. I want to freeze the reference as well as the object. In C++ it is possible to “freeze” (i.e. const) both a pointer to an object and the object itself. Is this possible in Ruby? a) Is my reasoning correct? b) Is there a way to do what I want? That is, freeze f or c[0] so that I get some sort of message/error/exception? c) Do my examples violate POLS? ---
**Author:** ![ralphshnelvar](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/e19adc/32.png) [@ralphshnelvar](https://www.ruby-forum.com/u/ralphshnelvar)\ **Post date:** [November 5, 2009, 3:17pm UTC](https://www.ruby-forum.com/t/freeze-not-freezing/178500/2 "2009-11-05T15:17:12Z")
Hi, In message “Re: Freeze not freezing” on Thu, 5 Nov 2009 23:05:28 +0900, Ralph S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) writes: |a) Is my reasoning correct? #freeze protect an object from modification. The reference is not the target of freezing. |b) Is there a way to do what I want? That is, freeze f or c[0] so that |I get some sort of message/error/exception? You can protect an array (or object) as a whole, since it is an object, so that c=[0,1] c.freeze c[0]=2 # =\> can’t modify frozen array (RuntimeError) but you cannot freeze any variables. |c) Do my examples violate POLS? No. Unlike C++, variables and references are not object in any sense in Ruby. From my viewpoint, C++ violates POLS. 😉 ``` matz. ``` ---
**Author:** ![ralphshnelvar](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/e19adc/32.png) [@ralphshnelvar](https://www.ruby-forum.com/u/ralphshnelvar)\ **Post date:** [November 5, 2009, 6:40pm UTC](https://www.ruby-forum.com/t/freeze-not-freezing/178500/3 "2009-11-05T18:40:55Z")
On 2009-11-05, Yukihiro M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > From my viewpoint, C++ violates POLS. 😉 Sturgeon’s Law: 90% of everything is crud. If you know this, C++ does not violate POLS. 🙂 -s ---
**Author:** ![ralphshnelvar](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/e19adc/32.png) [@ralphshnelvar](https://www.ruby-forum.com/u/ralphshnelvar)\ **Post date:** [November 5, 2009, 5:11pm UTC](https://www.ruby-forum.com/t/freeze-not-freezing/178500/4 "2009-11-05T17:11:20Z")
Matz, I deeply appreciate your answer. But I will repeat part of the question: Is there a way to detect … in the general case … that the reference to an object has changed? In a more C-like environment, a debugger is able to detect (via hardware) that a location in memory has changed. Is something similar available in Ruby? Where is the Ruby debugger (watch, etc.) documented? Ralph Thursday, November 5, 2009, 7:14:11 AM, you wrote: YM\> Hi, YM\> In message “Re: Freeze not freezing” YM\> on Thu, 5 Nov 2009 23:05:28 +0900, Ralph S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) writes: YM\> |a) Is my reasoning correct? YM\> #freeze protect an object from modification. The reference is not the YM\> target of freezing. YM\> |b) Is there a way to do what I want? That is, freeze f or c[0] so that YM\> |I get some sort of message/error/exception? YM\> You can protect an array (or object) as a whole, since it is an YM\> object, so that YM\> c=[0,1] YM\> c.freeze YM\> c[0]=2 # =\> can’t modify frozen array (RuntimeError) YM\> but you cannot freeze any variables. YM\> |c) Do my examples violate POLS? YM\> No. Unlike C++, variables and references are not object in any sense YM\> in Ruby. From my viewpoint, C++ violates POLS. 😉 YM\> matz.