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<p>Hi Eliot,</p>
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<p>> <span style="font-size: 12pt;">This may be a return address. If you ran this in the simulator you'd be able to see. Also try running it on the StackInterpreter and see what you get.</span></p>
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<div>Ah, this could be an explanation! I finally need to check out the VMMaker :-)</div>
<div>Wouldn't this be a memory leak vulnerability in the VM? Or don't we care about vulnerability issues in completely open systems such as Smalltalk at all?</div>
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<div>> <span style="font-size: 12pt;">What do you mean by "translates the #pushRcvr: bytecodes to another class"?</span>
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<div>Well, that's actually another issue. Since instance variable accesses are encoded <span style="font-family: Calibri, Helvetica, sans-serif, EmojiFont, "Apple Color Emoji", "Segoe UI Emoji", NotoColorEmoji, "Segoe UI Symbol", "Android Emoji", EmojiSymbols; font-size: 16px;">into
the bytecode</span> by index, not by name, you cannot reuse the bytecodes for different kinds of objects:</div>
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<div>c := Object newUniqueClassInstVars: 'foo bar' classInstVars: ''.</div>
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<div>d := Object newUniqueClassInstVars: 'bar baz' classInstVars: ''.</div>
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<div>c compile: 'bar ^ bar'.</div>
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<div>o := c new.</div>
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<div>p := d new.</div>
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<div>o instVarNamed: 'bar' put: 42.</div>
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<div>o bar. "42"</div>
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<div>p instVarNamed: 'bar' put: 42.</div>
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<div>p executeMethod: c >> #bar. "expected 42, but got nil"</div>
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<div>You always need to recompile the methods first ... This makes it impossible to add instance variables to traits, for example.</div>
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<div>Best,</div>
<div>Christoph</div>
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<div id="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 Eliot Miranda <eliot.miranda@gmail.com><br>
<b>Gesendet:</b> Samstag, 18. April 2020 21:05 Uhr<br>
<b>An:</b> The general-purpose Squeak developers list<br>
<b>Betreff:</b> Re: [squeak-dev] CompiledBlocks are fascinating</font>
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<div dir="ltr" class="gmail_attr">On Sat, Apr 18, 2020 at 10:31 AM Thiede, Christoph <<a href="mailto:Christoph.Thiede@student.hpi.uni-potsdam.de">Christoph.Thiede@student.hpi.uni-potsdam.de</a>> wrote:<br>
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<div>class := Object newSubclass.</div>
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<div>class addSelector: #foo: withMethod: (</div>
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<div><span style="white-space:pre-wrap"></span>[:x | x squared * 2] method as: CompiledMethod).</div>
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<div>class new foo: 3. "18"</div>
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<p>And you can even debug it :D</p>
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<p>This one is really crazy</p>
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<div>class := Object newUniqueClassInstVars: 'state' classInstVars: ''.</div>
<div>class addSelector: #foo withMethod: (</div>
<div><span style="white-space:pre-wrap"></span>[:x | gate] method as: CompiledMethod).</div>
<div>class new foo "-1.2045729113346377e-38"</div>
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<p>What the ...? Am I accessing any private method literals here?</p>
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<div style="color:rgb(0,0,0)">This may be a return address. If you ran this in the simulator you'd be able to see. Also try running it on the StackInterpreter and see what you get.</div>
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<p><span style="font-size:12pt">Then we only need a mechanism that translates the #pushRcvr: bytecodes to another class.</span><br>
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<div>I don't see you jumping to the metacircular interpreter in the above. What do you mean by "translates the #pushRcvr: bytecodes to another class"?</div>
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<p><span style="font-size:12pt">Best,</span><br>
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<p>Christoph</p>
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<div>_,,,^..^,,,_<br>
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<div>best, Eliot</div>
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