[Cuis-dev] [DEFECT] #copyFrom:count: for OrderedCollections

[Andres Valloud]

Right, "class" in the sense of "that which defines the behavior of the 
receiver".

On 2/6/24 11:00 AM, Luciano Notarfrancesco via Cuis-dev wrote:
> 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)
> 
> On Wed, Feb 7, 2024 at 01:57 Andres Valloud via Cuis-dev 
> <cuis-dev at lists.cuis.st <mailto:cuis-dev at lists.cuis.st>> wrote:
> 
>     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,
>      >
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