<div dir="auto">I would say not the class but the receiver is the only one with the full context, as illustrated by Text>>grownTo: (and other examples in my code)</div><div> <div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Feb 7, 2024 at 01:57 Andres Valloud via Cuis-dev <<a href="mailto:cuis-dev@lists.cuis.st">cuis-dev@lists.cuis.st</a>> wrote: </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;padding-left:1ex;border-left-color:rgb(204,204,204)">Be careful with that "false polymorphism" argument. Going down that route means you can ignore the receiver's class when you see a selector because a selector can only have one meaning. In a sense, it promotes selectors to operators. It should be pretty clear that collections like Array and Set should behave differently. Why is that being ignored? Consider this alternate interpretation. The root cause of this problem seems to be that some code has the expectation that species new: n can have exactly one meaning. The sender is ignoring the receiver class. Only the receiver class has that context. So the receiver class should be given the task of creating the new instance instead --- this is why arithmetic has double dispatching, for example. Andres. On 2/6/24 8:21 AM, Juan Vuletich via Cuis-dev wrote: > Let me also elaborate a bit on the rationale. > > In Smalltalk-80 (and every other Smalltalk system since then), the docs > will say that #new: will answer a collection of the requested size. But > it is not like that for Set, Dictionary, OrderedCollection and a few > others, that give a completely different semantics to this message. It > is no _that_ bad when the message is sent to an explicit class, although > you need to be aware of this. > > The real problem is when someone does `someCollection species new: > aNumber`. It gets really tricky to find out what is going to happen. > > This is a prime example of what I call "False Polymorphism". It looks > like a polymorphic message, but it is not. It is (at least) two sets of > senders/implementors, completely separated. This means obscure, > misleading code. It makes me sick. I fix every instance of this I see. > It rarely happens in the base Smalltalk-80 classes, but it is still wrong. > > Thanks, > -- Cuis-dev mailing list <a href="mailto:Cuis-dev@lists.cuis.st" target="_blank">Cuis-dev@lists.cuis.st</a> <a href="https://lists.cuis.st/mailman/listinfo/cuis-dev" rel="noreferrer" target="_blank">https://lists.cuis.st/mailman/listinfo/cuis-dev</a> </blockquote></div></div>