[Cuis-dev] String vs Symbol objects

[Nicolas Cellier]

Juan, the vm has support for immutability for quite some time, so it might
be time to use it for literals.

Le mer. 17 juil. 2024, 19:01, Juan Vuletich via Cuis-dev <
cuis-dev at lists.cuis.st> a écrit :

> On 7/17/2024 12:43 PM, Mark Volkmann via Cuis-dev wrote:
>
> Interesting! In this code I create two equivalent String objects, then
> modify a character in one of them. I wondered if it would do a "copy on
> write", but it did not. The modification affected both which was surprising
> to me.
>
> str1 := 'test'.
> str2 := 'test'.
> str1 at: 1 put: $b.
>
> In this case, str1 and str2 refer to the same object in memory, so both
> now have the value "best".
>
> I suppose the lesson is that literal strings in the same scope might
> (always?) use the same object in memory.
>
>
> The other lesson, at least to me, is that String mutation is bad (and
> ugly). It is generally better to create them anew, in a more functional
> style.
>
>
> On Wed, Jul 17, 2024 at 10:12 AM Juan Vuletich <juan at cuis.st> wrote:
>
>> On 7/17/2024 11:08 AM, Mark Volkmann via Cuis-dev wrote:
>>
>> When I enter the following lines in a Workspace, select them, and "Do
>> it", I get an AssertionFailure error:
>>
>> str1 := 'test'.
>> str2 := 'test'.
>> self assert: str1 ~~ str2.
>>
>> Ken, are you saying that you do not get that error?
>>
>> --
>> R. Mark Volkmann
>> Object Computing, Inc.
>>
>>
>> Side comment: an AssertionFailure is an Exception but not an Error (see
>> class hierarchy).
>>
>> You get the AssertionFailure if you select all three lines and evaluate
>> them together, but not if you evaluate them one by one.
>>
>> Truth is that str1 and str2 can not be assumed to be the same object. But
>> they can not be assumed to be different object either. The compiler is free
>> to reuse the string if it is easy enough.
>>
>> Cheers,
>>
>> --
>> Juan Vuletichcuis.stgithub.com/jvuletichresearchgate.net/profile/Juan-Vuletichindependent.academia.edu/JuanVuletichpatents.justia.com/inventor/juan-manuel-vuletichlinkedin.com/in/juan-vuletich-75611b3twitter.com/JuanVuletich
>>
>>
>
> --
> R. Mark Volkmann
> Object Computing, Inc.
>
>
>
> --
> Juan Vuletichcuis.stgithub.com/jvuletichresearchgate.net/profile/Juan-Vuletichindependent.academia.edu/JuanVuletichpatents.justia.com/inventor/juan-manuel-vuletichlinkedin.com/in/juan-vuletich-75611b3twitter.com/JuanVuletich
>
> --
> Cuis-dev mailing list
> Cuis-dev at lists.cuis.st
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>
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