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[OrderedCollection] add a reference or a copy?

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sergio_101

[OrderedCollection] add a reference or a copy?

I think my understanding of OrderedCollections has been incorrect for a very long time. I have never had a situation where it mattered, but in modeling a current project, I think I have been approaching it incorrectly.

Since I have been using Smalltalk, I assumed that a copy of an object is added to an OrderedCollection. A quick test shows that a reference to that object is added to the OrderedCollection.

I just wanted a sanity check on this. Is this true with all collections?

Thanks!

----
peace,
sergio
photographer, journalist, visionary

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Esteban A. Maringolo

Re: [OrderedCollection] add a reference or a copy?

Yes, it is the same. Everything is passed by "reference" (*).
And if you copy the collection you'll get two collections referencing
the same object.

E.g.
| a c1 c2 |
a := Object new.
b := OrderedCollection with: a.
b identityIncludes: a. "true"
c := b copy.
c identityIncludes: a. "true"

(*) Some objects like SmallIntegers are "immediate" objects, and could
be considered that they're passed by value.
E.g.
1 copy == 1 "true"

Regards,

Esteban A. Maringolo

On Wed, Jul 24, 2019 at 9:45 AM sergio ruiz <[hidden email]> wrote:

>
> I think my understanding of OrderedCollections has been incorrect for a very long time. I have never had a situation where it mattered, but in modeling a current project, I think I have been approaching it incorrectly.
>
> Since I have been using Smalltalk, I assumed that a copy of an object is added to an OrderedCollection. A quick test shows that a reference to that object is added to the OrderedCollection.
>
> I just wanted a sanity check on this. Is this true with all collections?
>
> Thanks!
>
>
> ----
> peace,
> sergio
> photographer, journalist, visionary
>
> Public Key: http://bit.ly/29z9fG0
> #BitMessage BM-NBaswViL21xqgg9STRJjaJaUoyiNe2dV
> http://www.codeandmusic.com
> http://www.twitter.com/sergio_101
> http://www.facebook.com/sergio101
>

sergio_101

Re: [OrderedCollection] add a reference or a copy?

Okay.

This makes the entire universe make more sense.

Thanks!

On Jul 24, 2019, at 9:30 AM, Esteban Maringolo <[hidden email]> wrote:

Yes, it is the same. Everything is passed by "reference" (*).
And if you copy the collection you'll get two collections referencing
the same object.

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Richard O'Keefe

Re: [OrderedCollection] add a reference or a copy?

In reply to this post by sergio_101

To a very good approximation, Smalltalk doesn't copy anything unless you ask it to.

In this respect it's just like Java, Python, Ruby, ECMAScript, and most OO languages.

C++ *does* like to copy things, but it is unusual.

On Thu, 25 Jul 2019 at 00:46, sergio ruiz <[hidden email]> wrote:

I think my understanding of OrderedCollections has been incorrect for a very long time. I have never had a situation where it mattered, but in modeling a current project, I think I have been approaching it incorrectly.

Since I have been using Smalltalk, I assumed that a copy of an object is added to an OrderedCollection. A quick test shows that a reference to that object is added to the OrderedCollection.

I just wanted a sanity check on this. Is this true with all collections?

Thanks!

----
peace,
sergio
photographer, journalist, visionary

Public Key: http://bit.ly/29z9fG0
#BitMessage BM-NBaswViL21xqgg9STRJjaJaUoyiNe2dV
http://www.codeandmusic.com
http://www.twitter.com/sergio_101
http://www.facebook.com/sergio101