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<p>Hi all,</p>
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<p>for a current project, I need to compare form or sound objects with each other, but I found out that they do not override #=, so for example, we get:</p>
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<p><span>(ColorForm extent: 1 @ 1) = (ColorForm extent: 1 @ 1) --> false</span></p>
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<p><span>Wasn't this implemented</span></p>
<p><span>a) simply because it looked like YAGNI?</span></p>
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b) for design reasons? For example, should (Form extent: 1 @ 1) be equal to (ColorForm extent: 1 @ 1) or not?</p>
c) for performance reasons? I don't know if there any guidelines for implement #= (except that you need to implement #hash as well), but is an equality comparison generally allowed to be an expensive operation if two objects are equal? If two large forms have
a different resolution or a different bitmap hash, comparison will be fast, but if they are equal, we will need to compare every single bit. Would this be okay or a no-go?</span>
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<p><span>If implementing #= as proposed is not possible, how would you think about implementing it as a keyword message on Form, e.g. #sameAs:?</span></p>
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<p><span>The same questions apply to the AbstractSound hierarchy, too, where I'm not sure whether two sounds being played for different duration should equal or not.</span></p>
<p><span>For a similar discussion, see also this thread: </span><a href="http://forum.world.st/FormInspector-or-also-Text-gt-gt-and-its-consequences-td5121599.html" class="OWAAutoLink"><span>[squeak-dev] </span><span style="font-size: 12pt;">FormInspector,
or also: Text>>#= and its consequences</span></a><span style="font-size: 12pt;">.</span><span></p>
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<div>Best,</div>
<div>Christoph</div>
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