[Pharo-project] Meanwhile, at another vm

Stefan Marr pharo at stefan-marr.de
Wed Apr 13 23:50:23 CEST 2011


On 13 Apr 2011, at 23:27, Göran Krampe wrote:

> On 04/13/2011 11:15 PM, Mariano Martinez Peck wrote:
>> On Wed, Apr 13, 2011 at 11:06 PM, Dave Mason <dmason at mason-rose.ca
>>    "We will also investigate support for hotswapping, the capability to
>>    modify the structure of classes at run time."
>> 
>>    So, yes, they planned to "investigate" a version of become:
>> 
>> 
>> How is that phrase related to #become:   ?   Modyfing the structure of a
>> class at runtime has nothing to do with a #become:
> 
> It depends. If "modify structure" means "modifying methods" then indeed it has little to do with become:. But if it means "changing the memory layout of the class by for example adding ivars" then it has to do with become: because it is needed to do instance migration from the old class to the new class.

There is no need for guessing, Google knows the answer:
  http://download.oracle.com/javase/6/docs/platform/jvmti/jvmti.html#RedefineClasses

"Instances of the redefined class are not affected -- fields retain their previous values. Tags on the instances are also unaffected."

"The redefinition may change method bodies, the constant pool and attributes. The redefinition must not add, remove or rename fields or methods, change the signatures of methods, change modifiers, or change inheritance. These restrictions may be lifted in future versions. "...



-- 
Stefan Marr
Software Languages Lab
Vrije Universiteit Brussel
Pleinlaan 2 / B-1050 Brussels / Belgium
http://soft.vub.ac.be/~smarr
Phone: +32 2 629 2974
Fax:   +32 2 629 3525




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