UIManager>>#defer: aBlock can be useful too.
defer: aBlock
" Evaluate the given Block in the UI thread as soon as there is nothing
scheduled. Evaluate immediately when there is no UI"
aBlock value
For some fun, check also GrowlMorph
10 timesRepeat: [
(GrowlMorph openWithLabel: 'The time' contents: DateAndTime now)
" vanishDelay: 1000;
resetVanishTimer".
World doOneCycle ].
inspect how vanishDelay: works, so that you can get the same kind of thing
as a JS
setTimeout(function(){ alert("Hello"); }, 3000);
Phil
On Mon, Oct 3, 2016 at 12:08 PM, Ben Coman <b...@openinworld.com> wrote:
>
> On Mon, Oct 3, 2016 at 3:49 PM, CodeDmitry <dimamakh...@gmail.com> wrote:
> > a JavaScript timeout is a function that takes a block and a period of
time,
> > and after this period of time, puts the block at the end of the event
> > queue, to be executed as soon as the runtime is done performing the
tasks in
> > front of it.
> >
> > I am not sure if Pharo has an event queue, so it's a bit harder to do
> > it(since without one you can't ensure only one thing happens at a time,
and
> > strange things can happen).
> >
> > That said, in simplest terms, imagine writing a clock app for Pharo,
which
> > updates time every second, in JS this would be done by setting an
interval
> > that ticks every 1000ms, and each time places the callback
function(block)
> > at the end of the event queue.
> >
> > Related: https://www.youtube.com/watch?time_continue=1&v=8aGhZQkoFbQ
>
> Pharo has a single threaded VM, but multiple green threads can run
concurrently.
> The closest to the event loop you are thinking of most likely the
> Morphic UI Process
> which you can see using World > Tools > Process Browser. When you
execute code
> from Playground it runs in that Process (note what Smalltalk
> historically (circa 1970s?) has
> called a Process is today more commonly know as a Green Thread)
>
> If you select Morphic UI Process you will see its call stack on the
> right, where an interesting method is WorldState>>doOneCycleFor:
> You can gain some insight by turning on auto-update in the Process
> Browser, then open a Browser on WorldState>>doOneCycleFor:
> and put "self haltOnce" at the top, then enable it via...
> Pharo 5: World > System > Enable halt/inspect once.
> Pharo 6: World > Debugging > Enable all break/inspect once.
>
> You will see in the Process Browser that a new Morphic UI Process is
> spawned, and the original Morphic UI Process call stack now has
> #debugProcess at the top
> and a debug window appears that you can step through. Note, since two
> UI loops are executing here, the image may lock up, but usually its
> fine so hey! live on the edge!
>
> In #runStepMethodsIn: you'll see "queue := self class
> deferredUIMessages" for which you enqueue items like this...
>
http://forum.world.st/Issue-3562-in-pharo-Deferred-UI-messages-executed-slowly-td3228060.html
>
> After processing the deferred UI messages, each Morph's #step method
> is processed by #runLocalStepMethodsIn:
> refer... http://wiki.squeak.org/squeak/2096
>
> The display is then rendered by #displayWorldSafely: calling...
> --> #displayWorld
> --> #displayWorld:submorphs:
> which then is a lot to trace through, but depending on the graphics
> back end eventually ends up calling...
> Canvas>>fullDrawMorph: which ultimately invokes one of many #drawOn:
> or...
> AthensCanvas>>fullDrawMorph: which ultimately invokes one of many
> #drawOnAthensCanvas:
>
>
> So, for a regular timed UI animation, you would define your custom
> morph's #step and #stepTime methods,
> and for lower level stuff you would fork like Dennis suggests.
>
> cheers -ben
>
>
