[Vm-dev] Re: Reproducible way to crash Cog ( [Lsehub-staff] Strange behavior )

[Eliot Miranda]

On Thu, Dec 9, 2010 at 3:10 AM, Henrik Johansen <
henrik.s.johansen at veloxit.no> wrote:

>
>
> On Dec 8, 2010, at 11:42 00PM, Eliot Miranda wrote:
>
>
>
> On Wed, Dec 8, 2010 at 2:14 PM, Andreas Raab <andreas.raab at gmx.de> wrote:
>
>>
>> On 12/8/2010 1:58 PM, Igor Stasenko wrote:
>>
>>> I never used this prim before, so i didn't knew that it takes the
>>> class of argument,
>>> instead an argument itself as a class to which replace receiver's class.
>>>
>>
> VisualWorks also started off with a changeClassToThatOf: primitive which
> took an instance.  We fixed that by providing behavior>adoptInstance:. This
> still has to extract format info form the receiver (a class) but at least
> the primitive can assume the receiver is a valid behavior and it only has to
> check if the argument is suitable as an instance of the class.
>
> I wrote this for Cog also, see primitiveAdoptInstance, #160, so if you find
> this more convenient you can use it; find attached.
>
> HTH
> Eliot
>
>
> Weee, I've missed the adoptInstance: method!
> While I agree it's nothing to use regularly, it can be fun to play around
> with.
> F.ex, I used the primitive some time ago in an evil/clever experiment  to
> remove depth instVar / methods which branch on depth from Form.
>
> So, to have a method which works on both Cog and non-Cog, could we write:
>
> Behavior >> #adoptInstance: anInstance
> <primitive: 160 error: ec>
> ^anInstance changeClassToThatOf: self basicNew
>
> Or are the failure cases different?
>

 I think it'll be close enough.  Go for it.


>
> Cheers,
> Henry
>
>
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