[Vm-dev] Bug in #instVarAt:put: for read-only objects

[Eliot Miranda]

Hi Clément,

    is it too late to take a look at the VisualWorks code and use the same class names and selectors they use?  IIRC it is NoMidificationError.  It may make e.g. Gemstone's job easier if there is some consistency.

_,,,^..^,,,_ (phone)

> On Jan 5, 2018, at 5:22 AM, Clément Bera <bera.clement at gmail.com> wrote:
> 
> Hi,
> 
> No this is not a bug.
> 
> This needs to be handled in the primitive failure code in the image, the method should be something like that :
> 
> Object>>instVarAt: index put: anObject
> 	<primitive: 174 error: ec>
>         self isReadOnlyObject ifTrue: [(ModificationForbidden for: self atInstVar: index with: anObject) signal]
> 	self primitiveFailed
> 
> All primitive fall-back code triggering object mutation should be rewritten this way, especially primitives such as #at:put:, #instVarAt:put:, etc.
> 
> Cheers
> 
>> On Fri, Jan 5, 2018 at 1:42 PM, Norbert Hartl <norbert at hartl.name> wrote:
>>  
>> If I do 
>> 
>> (#foo -> #bar)
>> 	beReadOnlyObject;
>> 	value: #baz
>> 
>> it throws
>> 
>> ModificationForbidden:  #foo->#bar is read-only, hence its field 2 cannot be modified with #baz
>> 
>>  which is as expected. But if I do
>> 
>> (#foo -> #bar)
>> 	beReadOnlyObject;
>> 	instVarNamed: #value put: #baz
>> 
>> I get
>> 
>> PrimitiveFailed: primitive #instVarAt:put: in Association failed
>> 
>> I think this a bug, no?
>> 
>> Norbert
>> 
> 
> 
> 
> -- 
> Clément Béra
> Pharo consortium engineer
> https://clementbera.wordpress.com/
> Bâtiment B 40, avenue Halley 59650 Villeneuve d'Ascq
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