I added myself the missing method as an extension in my package. This
will do it for now.

Hilaire

2009/2/26 Stéphane Ducasse <[email protected]>:
> marcus
>
> to help hilaire what woul dbe the fall back
> and deprecated version so that magma works?
>
> Stef
> On Feb 26, 2009, at 10:54 AM, Marcus Denker wrote:
>
>>
>> On 26.02.2009, at 10:37, Hilaire Fernandes wrote:
>>
>>> It looks like Association>>isSpecialWriteBinding is gone in Pharo.
>>> Can
>>> someone confirm it?
>>>
>>> It hurt because it is used by Magma..
>>>
>>
>> Yes. cleanup of un-used code.
>>
>> The story was that: In the SystemDictionary ("Smalltalk") there are
>> the
>> classes. Technically, Dictionaries are collections of Associations.
>>
>> Now, "Smalltalk" has globals *and* classes. Which means, we can do
>>
>> Object := nil.
>>
>> And everthing is dead.
>>
>> This is especially a problem in an ende-user scripting systems (e.g.
>> something
>> more powerful than etoys, but targeted at non-programmers).
>>
>> Sometime in the last century, someone started to work on making Squeak
>> more stable (or
>> secure for some meaning of secure).
>>
>> Now, one can fix the assignment problem in two places:
>>
>> A) name analysis of the compiler. The place where all the other
>> warning are generated.
>> B) replacing the association in the Smalltalk dictionary by one that
>> can not be changed.
>>    (here "value:" raises an exception).
>>
>> The isSpecialWriteBinding was the test to check if the binging was
>> read=only or read/write.
>> Some classes where referenced using a read-only binging (those that
>> where very old), but
>> all new classes where referenced using a normal association.
>>
>> There was no code in the image that would create
>> ReadOnlyVariableBindings. It was never used
>> in this century. And: is that really at the right level, that change?
>> For controlling assignments,
>> the compiler's checking phase is much better.
>>
>> If one wants to make the structure of the sytem (the "structural
>> model" in the sense of structural
>> reflection) read-only, this does not help at all. Remember, this hack
>> just touches *one* place in the
>> object graph that starts with "Smalltalk". It does not, for example,
>> secure the method-dictonary. Nor
>> changes to the inhertance hierarchy.
>>
>> This is actually a very cool topic of research... and we are
>> incidentally actually working just now
>> on a paper that shows one cool direction of providing "read only"
>> views on shared object graphs like
>> the one that represents the structure of the system.
>>
>>       Marcus
>>
>>
>> --
>> Marcus Denker  --  [email protected]
>> http://www.marcusdenker.de
>>
>>
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>
>
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-- 
http://blog.ofset.org/hilaire

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