[squeak-dev] The Trunk: System-ul.253.mcz
leves at elte.hu
Wed Feb 17 21:22:11 UTC 2010
On Tue, 16 Feb 2010, Juan Vuletich wrote:
> Levente Uzonyi wrote:
>> Why is MessageTally using the class variable Timer instead of an instance
> I really don't know. Perhaps to make it clear that nested tallies are not
> supported? BTW, I've just looked in Squeak 1.1, and it uses the Timer
> variable the same way. Hey, I even opened Apple Smalltalk-80, and it is the
> same too :).
Thanks for the research, it's good to know the original design decision.
Too bad the class comment doesn't tell anything about it. We should fix
>> I added a new instance variable timer to MessageTally, replaced all
>> occurence of Timer to timer, removed the #ifNotNil: checks and successfully
>> profiled the tests. Is anything wrong with this approach?
> I just tried the same. It seems to work. But it seems whoever wrote
> MessageTally knew what he was doing. Using an instance variable would have
> been the obvious choice. But they decided to use a class variable. Mhhh. I
> looked at the old books and found nothing. Looking at Squeak 1.1. and
> Smalltalk-80, I believe it was because at that time there was no #ensure: and
> they wanted to be sure to kill the process, as it won't stop if you got a
> walkback or pressed alt-.. So I guess your proposal is ok. But on the other
> hand, I see no value in supporting nested tallies, and your proposal would
> require some testing.
> So, if you're willing to see how it works, and perhaps revert it if some
> problem arises, I'd say go ahead with it.
I agree there's no value in nested tallies, MessageTally doesn't give
meaningful results even if timer is an instance variable in this case.
And I think you're right, MessageTally should raise an error if a timer
process is already running, but the error should be raised when the
second process is about to be created, not when the first is about to be
I realized that the timer process is terminated by Debugger >>
#process:controller:context: and not nested tallies when running all the
tests profiled, since no MessageTally is created directly by tests.
So replacing Timer with an instance variable is not a good idea, since the
debugger has to stop the timer process somehow, but maybe
suspending/resuming is enough.
> Juan Vuletich
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