[Cuis-dev] [Pharo-dev] Can we have subclasses of Process?

Eliot Miranda eliot.miranda at gmail.com
Thu Aug 17 14:28:07 CDT 2017

Hi Denis,

    as others have pointed out one can subclass Process.  One can also add
instance variables to Process.  The constraint is that the first four (*)
instance variables must be left unaltered.  The VM makes use of the first

Object subclass: #Link
instanceVariableNames: 'nextLink'
Link subclass: #Process
instanceVariableNames: 'suspendedContext priority myList...

(*five when we have the multithreaded FFI, the fifth being threadId used to
bind processes to specific OS threads when required)

The same goes for ProcessorScheduler - the VM uses quiescentProcessLists &
activeProcess, and Semaphore - the VM uses firstLink lastLink &

On Thu, Aug 17, 2017 at 5:03 AM, Denis Kudriashov <dionisiydk at gmail.com>

> Hi.
> Is it allowed to subclass Process?  I remember that there were some
> problems with it but I could not find any information.
> Generally I think about system processes which can be represented by
> concrete subclasses. For example explicit UIProcess can be used to remove
> many #isUIProcess conditions from system.
> Best regards,
> Denis

best, Eliot
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