On Tue, 29 Oct 2019, Marcel Taeumel wrote:

> Hi Christoph.
> > However, currently, a #deprecated call in a drawing method makes the image unusable ...
> 
> Yes, there is a lot of room for improvement in Squeak's strategy to keep the image alive and in a recoverable state. Annoying things include errors in event handlers (such as #mouseOver:) and the thing about Warnings you
> mentioned for #displayWorldSafely.
> 
> Since the exception mechanism can be used to implement dynamic scope (see CurrentReadOnlySourceFiles), we should never catch Exception in general to install such handlers.
> 
> Warning might be a nice addition to #displayWorldSafely.
> 
> [Error] bench '219,000,000 per second. 4.57 nanoseconds per run.'
> [Error, Halt] bench '11,900,000 per second. 84.4 nanoseconds per run.'
> [Error, Halt, Warning] bench '9,910,000 per second. 101 nanoseconds per run.'

#bench is not suitable to measure things that are fairly quick, because [] 
bench doesn't give 0 ns. It's not too far off, but definitely not 
accurate, especially if you compare ratios.

#bench doesn't measure the effects of allocation/gc well. The last two 
code puts pressure on the garbage collector.

> 
> Since this is called only once to fourteen times per frame (see DamageRecorder) -- but usually only once -- we are good with 100 nanoseconds, given that 60 frames-per-second translate to 16 666 667 nanoseconds per frame.

Not all machines (physical and virtual) running Squeak are as fast as 
yours. What's 100ns on your machine, may take up to 3 magnitudes longer 
on others. In that case, you only have 16 666 microseconds to render, and 
you spend 100 microseconds on something that could be almost 0.

If there were a class variable holding the exception set, it could be 
reused with no additional cost. It would also let users to add their own 
exceptions to the set without modifying Trunk code.

Levente

> 
> Best,
> Marcel
>
>       Am 25.10.2019 20:46:52 schrieb Thiede, Christoph <christoph.thiede at student.hpi.uni-potsdam.de>:
>
>       I see, but isn't it just their existence what we want to test for to prevent from loads of Debuggers appearing?
>
>       Or should we go the other way around and signal a "DebuggerRaisedNotification" each time before opening a debugger?
> 
>
>       However, currently, a #deprecated call in a drawing method makes the image unusable ...
> 
> _________________________________________________________________________________________________________________________________________________________________________________________________________________________________
> Von: Squeak-dev <squeak-dev-bounces at lists.squeakfoundation.org> im Auftrag von Taeumel, Marcel
> Gesendet: Mittwoch, 23. Oktober 2019 15:48:15
> An: John Pfersich via Squeak-dev
> Betreff: Re: [squeak-dev] The Trunk: System-mt.1093.mcz  
> > Why isn't it sufficient to test for UnhandledError instead? Otherwise, we would also need to test for Warning etc. ...
> UnhandledError and UnhandledWarning are (private) implementation details of Squeak's exception handling mechanism. They should never be exposed to (or used by) applications/frameworks.
> 
> Best,
> Marcel
>
>       Am 22.10.2019 18:50:59 schrieb Thiede, Christoph <christoph.thiede at student.hpi.uni-potsdam.de>:
>
>       Why isn't it sufficient to test for UnhandledError instead? Otherwise, we would also need to test for Warning etc. ...
> 
> _________________________________________________________________________________________________________________________________________________________________________________________________________________________________
> Von: Squeak-dev <squeak-dev-bounces at lists.squeakfoundation.org> im Auftrag von Taeumel, Marcel
> Gesendet: Dienstag, 15. Oktober 2019 13:18:26
> An: gettimothy via Squeak-dev
> Betreff: Re: [squeak-dev] The Trunk: System-mt.1093.mcz  
> Yeah, I wonder whether we should expand "Error" to "Error, Halt"?
> Best,
> Marcel
>
>       Am 15.10.2019 12:45:42 schrieb Balázs Kósi <rebmekop at gmail.com>:
>
>       Hi Hannes!
> 
> This morning I've just run into this exact same situation: putting a halt into a method, called by a morph's #drawOn:
> makes the image unusable.
> 
> The problem stems from WorldState >> displayWorldSafely: being safe only for Errors and not for other kind of
> Exceptions, and Halt being only an Exception not an Error.
> 
> For a quick fix add Halt to the handled exceptions in #displayWorldSafely:
> [aWorld displayWorld. finished := true] on: Error, Halt do: [:ex |
> Balázs
> 
> 
>