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<p>Hi Levente, thanks for the feedback.</p>
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<div class="x__rp_T4" id="x_Item.MessagePartBody">> <span style="font-size:12pt">What's your use-case?</span>
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<div>Actually not a real use case, I was just confused by the confusion of both methods.</div>
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<div>But I would find it cool if my first code example would work, for the best support of converting arbitrary objects between each other.</div>
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<div>Best,</div>
<div>Christoph</div>
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<div id="x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>Von:</b> Squeak-dev <squeak-dev-bounces@lists.squeakfoundation.org> im Auftrag von Levente Uzonyi <leves@caesar.elte.hu><br>
<b>Gesendet:</b> Freitag, 3. Januar 2020 23:14:07<br>
<b>An:</b> The general-purpose Squeak developers list<br>
<b>Betreff:</b> Re: [squeak-dev] Object >> #copyFrom: vs Object >> #copySameFrom:</font>
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<div class="PlainText">Hi Christoph,<br>
<br>
On Fri, 3 Jan 2020, Thiede, Christoph wrote:<br>
<br>
> <br>
> Hi Levente,<br>
> <br>
> <br>
> I don't get that.<br>
> <br>
> <br>
> Did I interpret your explanation correctly?<br>
<br>
Yes, you did. I just checked why it doesn't work, and it turned out I <br>
misremembered how it actually works.<br>
The primitive's comment is:<br>
<br>
Copy the state of the receiver from the argument.<br>
Fail if receiver and argument are of a different class.<br>
Fail if the receiver or argument are contexts (because of context-to-stack mapping).<br>
Fail if receiver and argument have different lengths (for indexable objects).<br>
Fail if the objects are not in a fit state to be copied (e.g. married contexts and Cogged methods<br>
<br>
So, it'll fail, because the classes are not the same (an artifical <br>
limitation IMO).<br>
The fallback code will only copy slots of the same index if they have the <br>
same name (also an artificial limitation).<br>
<br>
What's your use-case?<br>
<br>
<br>
Levente<br>
<br>
> <br>
><br>
> fooClass := Object newUniqueClassInstVars: 'a b' classInstVars: ''.<br>
> barClass := Object newUniqueClassInstVars: 'b c' classInstVars: ''.<br>
> foo := fooClass new.<br>
> bar := barClass new<br>
> instVarNamed: #b put: 2;<br>
> instVarNamed: #c put: 3;<br>
> yourself.<br>
> foo copyFrom: bar.<br>
> foo instVarNamed: #b "expected: 2, actual: nil"<br>
> <br>
> <br>
> Otherwise, if I put #b as the first instvar in both classes, #copyFrom: and #copySameFrom: won't differ again ...<br>
> <br>
> <br>
> Best,<br>
> <br>
> Christoph<br>
> <br>
> <br>
> _________________________________________________________________________________________________________________________________________________________________________________________________________________________________<br>
> Von: Squeak-dev <squeak-dev-bounces@lists.squeakfoundation.org> im Auftrag von Levente Uzonyi <leves@caesar.elte.hu><br>
> Gesendet: Freitag, 3. Januar 2020 19:05 Uhr<br>
> An: The general-purpose Squeak developers list<br>
> Betreff: Re: [squeak-dev] Object >> #copyFrom: vs Object >> #copySameFrom: <br>
> Hi Christoph,<br>
> <br>
> The two methods are different. #copyFrom: copies variables by index while<br>
> #copySameFrom: copies variables by name.<br>
> So, if you have an object named foo of class Foo with 2 instance variables<br>
> a and b, and an object named bar of class Bar with 2 instance variables b<br>
> and c, then foo copyFrom: bar will copy bar's b to foo's a, and bar's c to<br>
> foo's b. #copySameFrom: will copy bar's b to foo's b and leave foo's a as<br>
> is.<br>
> <br>
> Levente<br>
> <br>
> <br>
> On Fri, 3 Jan 2020, Thiede, Christoph wrote:<br>
> <br>
> ><br>
> > Hi all,<br>
> ><br>
> ><br>
> > I don't get the actual difference between #copyFrom: and #copySameFrom:.<br>
> ><br>
> ><br>
> > The latter looks more "modern" to me, as it uses a primitive and has several implementors.<br>
> ><br>
> > In my opinion, none of them actually matches its description ("Copy to myself all instance variables [named the same in | I have in common with] otherObject"). The following leaves o2 empty:<br>
> ><br>
> ><br>
> > c1 := Object newUniqueClassInstVars: 'foo bar' classInstVars: ''.<br>
> > c2 := Object newUniqueClassInstVars: 'bar foo' classInstVars: ''.<br>
> > o1 := c1 new<br>
> > instVarNamed: #foo put: 6;<br>
> > instVarNamed: #bar put: 7.<br>
> > o2 := o1 as: c2.<br>
> > o2 instVarAt: 1 "nil".<br>
> ><br>
> > o2 copySameFrom: o1.<br>
> > o2 instVarAt: 1 "nil".<br>
> ><br>
> ><br>
> > Question: Could we deprecate #copySameFrom:, and in #copyFrom:, copy *all* matching instvars without respecting their order? Or did I miss any intended difference in behavior?<br>
> ><br>
> > Best,<br>
> > Christoph<br>
> ><br>
> ><br>
> ><br>
> <br>
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