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nacho

Sep 25, 2014; 6:14pm

Passed by references and by value

238 posts

Hi,
In PBE says that ordinary objects' ivars are passed by references and small integers are passed by value.
Is there a way to know if a class is passed by reference or by value?
Only small integers are passed as value?
Thanks in advance
Nacho

Nacho Smalltalker apprentice. Buenos Aires, Argentina.

Mark Rizun

Sep 25, 2014; 6:20pm

Re: Passed by references and by value

194 posts

Hi,

Most classes are passed by reference including those that were defined by user.

But classes like integer are passed by value.

I think it's similar to C#.

I may be wrong, so better wait for another more competent reply:)

Best,

Mark

2014-09-25 21:14 GMT+03:00 nacho <[hidden email]>:

Hi,
In PBE says that ordinary objects' ivars are passed by references and small
integers are passed by value.
Is there a way to know if a class is passed by reference or by value?
Only small integers are passed as value?
Thanks in advance
Nacho

-----
Nacho
Smalltalker apprentice.
Buenos Aires, Argentina.
--
View this message in context: http://forum.world.st/Passed-by-references-and-by-value-tp4780289.html
Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.

... [show rest of quote]

Esteban A. Maringolo

Sep 25, 2014; 6:28pm

Re: Passed by references and by value

2343 posts

In reply to this post by nacho

2014-09-25 15:14 GMT-03:00 nacho <[hidden email]>:
> Hi,
> In PBE says that ordinary objects' ivars are passed by references and small
> integers are passed by value.
> Is there a way to know if a class is passed by reference or by value?

> Only small integers are passed as value?

Yes.

It has to do with the object headers, SmallIntegers are embedded in the OH.

Esteban A. Maringolo

Mark Rizun

Sep 25, 2014; 6:35pm

Re: Passed by references and by value

194 posts

> Only small integers are passed as value?

Yes.

It has to do with the object headers, SmallIntegers are embedded in the OH.

What about Float, for example?

abergel

Sep 25, 2014; 6:59pm

Re: Passed by references and by value

5677 posts

Floats are passed as values.

Objects that are passed as values should be immutable, as floats and integers.

Alexandre

--
_,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:
Alexandre Bergel http://www.bergel.eu
^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;.

On Sep 25, 2014, at 3:35 PM, Mark Rizun <[hidden email]> wrote:

> Only small integers are passed as value?

Yes.

It has to do with the object headers, SmallIntegers are embedded in the OH.

What about Float, for example?

Esteban A. Maringolo

Sep 25, 2014; 7:04pm

Re: Passed by references and by value

2343 posts

In reply to this post by Mark Rizun

I forgot. Floats too.

And I think that's it.

Esteban A. Maringolo

2014-09-25 15:35 GMT-03:00 Mark Rizun <[hidden email]>:

>> > Only small integers are passed as value?
>>
>> Yes.
>>
>> It has to do with the object headers, SmallIntegers are embedded in the
>> OH.
>
>
> What about Float, for example?
>

stepharo

Sep 25, 2014; 7:52pm

Re: Passed by references and by value

5159 posts

In reply to this post by nacho

> Hi,
> In PBE says that ordinary objects' ivars are passed by references and small
> integers are passed by value.

Strange I do not remember having written that.
Especially because in Smalltalk this has no real interest.

> Is there a way to know if a class is passed by reference or by value?
In Smalltalk consider that everything is an object and that you pass a
reference to the object.

> Only small integers are passed as value?
> Thanks in advance
> Nacho
>
>
>
>
>
> -----
> Nacho
> Smalltalker apprentice.
> Buenos Aires, Argentina.
> --
> View this message in context: http://forum.world.st/Passed-by-references-and-by-value-tp4780289.html
> Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.
>
>

... [show rest of quote]

nacho

Sep 25, 2014; 7:55pm

Re: Passed by references and by value

238 posts

This post was updated on Sep 25, 2014; 7:56pm.

stepharo wrote

> Hi,
> In PBE says that ordinary objects' ivars are passed by references and small
> integers are passed by value.

Strange I do not remember having written that.
Especially because in Smalltalk this has no real interest.

Well you also wrote that :p

"Deep in the implementation of Smalltalk, there are three different kinds of objects. There are (1) ordinary objects with instance variables that are passed by references, there are (2) small integers that are passed by value, and there are (3) indexable objects like arrays that hold a contiguous portion of memory. The beauty of Smalltalk is that you normally don’t need to care about the differences between these three kinds of object."

> Is there a way to know if a class is passed by reference or by value?
In Smalltalk consider that everything is an object and that you pass a
reference to the object.
> Only small integers are passed as value?
> Thanks in advance
> Nacho
>
>
>
>
>
> -----
> Nacho
> Smalltalker apprentice.
> Buenos Aires, Argentina.
> --
> View this message in context: http://forum.world.st/Passed-by-references-and-by-value-tp4780289.html
> Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.
>
>

Nacho Smalltalker apprentice. Buenos Aires, Argentina.

Clément Béra

Sep 26, 2014; 6:07am

Re: Passed by references and by value

1053 posts

Depending on the VM you use, different objects are passed by values.

Currently -> only smallintegers

on Spur 32 bits VM -> smallintegers and characters

on Spur 64 bits VM -> smallintegers, characters and smallfloat

But as Stef said it does not really matter in smalltalk.

2014-09-25 21:55 GMT+02:00 nacho <[hidden email]>:

"
stepharo wrote
>> Hi,
>> In PBE says that ordinary objects' ivars are passed by references and
>> small
>> integers are passed by value.
>
> Strange I do not remember having written that.
> Especially because in Smalltalk this has no real interest.
>
>
> Well you also wrote that :p
>
> "Deep in the implementation of Smalltalk, there are three different kinds
> of objects. There are (1) ordinary objects with instance variables that
> are passed by references, there are (2) small integers that are passed by
> value, and there are (3) indexable objects like arrays that hold a
> contiguous portion of memory. The beauty of Smalltalk is that you normally
> don’t need to care about the differences between these three kinds of
> object.
>
>> Is there a way to know if a class is passed by reference or by value?
> In Smalltalk consider that everything is an object and that you pass a
> reference to the object.
>> Only small integers are passed as value?
>> Thanks in advance
>> Nacho
>>
>>
>>
>>
>>
>> -----
>> Nacho
>> Smalltalker apprentice.
>> Buenos Aires, Argentina.
>> --
>> View this message in context:
>> http://forum.world.st/Passed-by-references-and-by-value-tp4780289.html
>> Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.
>>
>>

-----
Nacho
Smalltalker apprentice.
Buenos Aires, Argentina.
--
View this message in context: http://forum.world.st/Passed-by-references-and-by-value-tp4780289p4780321.html

Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.

... [show rest of quote]

Marcus Denker-4

Sep 26, 2014; 6:22am

Re: Passed by references and by value

7582 posts

On 26 Sep 2014, at 08:07, Clément Bera <[hidden email]> wrote:

> Depending on the VM you use, different objects are passed by values.
>
> Currently -> only smallintegers
> on Spur 32 bits VM -> smallintegers and characters
> on Spur 64 bits VM -> smallintegers, characters and smallfloat
>
> But as Stef said it does not really matter in smalltalk.
>

Yes, even for these cases you pass the *reference*, only that the reference
happens to encode the value.

Marcus

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Marcus Denker-4

Sep 26, 2014; 6:24am

Re: Passed by references and by value

7582 posts

In reply to this post by Esteban A. Maringolo

On 25 Sep 2014, at 20:28, Esteban A. Maringolo <[hidden email]> wrote:

> 2014-09-25 15:14 GMT-03:00 nacho <[hidden email]>:
>> Hi,
>> In PBE says that ordinary objects' ivars are passed by references and small
>> integers are passed by value.
>> Is there a way to know if a class is passed by reference or by value?
>
>> Only small integers are passed as value?
>
> Yes.
>
> It has to do with the object headers, SmallIntegers are embedded in the OH.
>

In the *reference*, not the header. The reference points to a header for a normal
object, for small-integers the reference *is* the integer value. This means that
there is no header for the integers.

Marcus

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Henrik Sperre Johansen

Sep 26, 2014; 12:19pm

Re: Passed by references and by value

1774 posts

On 26 Sep 2014, at 8:24 , Marcus Denker <[hidden email]> wrote:

>
> On 25 Sep 2014, at 20:28, Esteban A. Maringolo <[hidden email]> wrote:
>
>> 2014-09-25 15:14 GMT-03:00 nacho <[hidden email]>:
>>> Hi,
>>> In PBE says that ordinary objects' ivars are passed by references and small
>>> integers are passed by value.
>>> Is there a way to know if a class is passed by reference or by value?
>>
>>> Only small integers are passed as value?
>>
>> Yes.
>>
>> It has to do with the object headers, SmallIntegers are embedded in the OH.
>>
>
> In the *reference*, not the header. The reference points to a header for a normal
> object, for small-integers the reference *is* the integer value. This means that
> there is no header for the integers.
>
> Marcus

... [show rest of quote]

So, a succinct phrasing indifferent to object format, using a relatively well-defined term, would be:
Only immediate objects are passed by value.

(Which means you have to explain immediate objects, as markus did)

Cheers,
Henry

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abergel

Sep 26, 2014; 2:37pm

Re: Passed by references and by value

5677 posts

In reply to this post by stepharo

Indeed, one should not care about copy by value / reference in Pharo.

Alexandre

--
_,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:
Alexandre Bergel http://www.bergel.eu
^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;.

On Sep 25, 2014, at 4:52 PM, stepharo <[hidden email]> wrote:

Hi,
In PBE says that ordinary objects' ivars are passed by references and small
integers are passed by value.

Strange I do not remember having written that.
Especially because in Smalltalk this has no real interest.

Is there a way to know if a class is passed by reference or by value?
In Smalltalk consider that everything is an object and that you pass a reference to the object.
Only small integers are passed as value?
Thanks in advance
Nacho

-----
Nacho
Smalltalker apprentice.
Buenos Aires, Argentina.
--
View this message in context: http://forum.world.st/Passed-by-references-and-by-value-tp4780289.html
Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.

... [show rest of quote]

... [show rest of quote]