[Vm-dev] Having a specific class for temp vectors

[Levente Uzonyi]

On Sat, 21 Nov 2015, stephane ducasse wrote:

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> On 21 Nov 2015, at 17:29, Levente Uzonyi <leves at elte.hu> wrote:
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>> I checked how the implementation actually works, and I came to the conclusion that using a separate class might be a good idea, because there's no easy way to tell if an Array returned by #tempAt: is a temp vector with some temporaries or just a regular array in a temporary variable. This means that returning the wrapped objects would probably require a lot more changes.
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>> I'd still refrain from the additional changes which would introduce some overhead in the methods you listed. Why?
>> For #become:, I understand the reason why you'd want it to add the check, but there are so many other cases to handle (e.g.: "true become: false") if you want to make #become: safer.
>> For immutability, I don't see the reason for the restriction. What if I, as the programmer, want to do a little hack, and overwrite the value of a temporary variable of a given block. That should work IMHO. So making the array immutable is fine, making the user unable to make it mutable is not.
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> I think that a language implementation should support reasonable extensions with good reason (I do not see a good scenario for overwriting the value of a temp in a block - do you have a real example in mind) and language implementors should get space for optimisation.

>From the debugger you can change the value of all variables, including 
temporaries, which should stay that way.
What Clement suggest would make the VM slower, not faster, due to the 
additional checks.

Levente

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>> Levente
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>> On Sat, 21 Nov 2015, Levente Uzonyi wrote:
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>>> Wouldn't it be a better solution to change #tempAt: to return the wrapped object instead of the temp vector?
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>>> Levente
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