Etoys: Etoys-Richo.100.mcz

Actually, I think that when single-line-stepping with Richo's new Scriptor debugger feature, if an object's pen is down and a line of script is executed that moves the object, a pen trail *should* be put down, even if "batchPenTrails" is in effect.  A semantic argument for this choice can be made, given the definition of "batchPenTrails", but my preference is based just on common sense and least surprise.

(And anyone with experience with debugging any live system knows that the when you single-step at leisure through something that normally is happening in a flash, you're running the code in a different context and you're going to encounter differences...).

If doing turtle-graphics of the sort in Karl's example, one probably does not want "batchPenTrails" to be turned on in the first place.

 -- Scott

On Feb 3, 2012, at 11:31 PM, [hidden email] wrote:

> Ricardo Moran uploaded a new version of Etoys to project Etoys:
> http://source.squeak.org/etoys/Etoys-Richo.100.mcz
>
> ==================== Summary ====================
>
> Name: Etoys-Richo.100
> Author: Richo
> Time: 3 February 2012, 8:30:10 pm
> UUID: f95a393c-27a3-e541-a345-4fd66b47cd8f
> Ancestors: Etoys-kfr.99
>
> * Fixed step button behavior when #batchPenTrails option is on.
>
> =============== Diff against Etoys-kfr.99 ===============
>
> Item was changed:
>  Object subclass: #EtoysDebugger
> +     instanceVariableNames: 'scriptEditor next timesToRepeat highlighter startingPosition'
> -     instanceVariableNames: 'scriptEditor next timesToRepeat highlighter'
>       classVariableNames: ''
>       poolDictionaries: ''
>       category: 'Etoys-Debugger'!
>
> Item was changed:
> + ----- Method: EtoysDebugger>>delete (in category 'initialization') -----
> - ----- Method: EtoysDebugger>>delete (in category 'as yet unclassified') -----
>  delete
>       highlighter ifNotNil: [:h | h delete]!
>
> Item was changed:
>  ----- Method: EtoysDebugger>>evaluateNextTile (in category 'evaluating') -----
>  evaluateNextTile
> +     [next = (scriptEditor tiles at: 1 ifAbsent: [nil])
> +             ifTrue: ["We are about to evaluate the first tile"
> +                     self updateStartingPosition].
> +     self trailMorph batchPenTrails
> +             ifTrue: [self evaluateNextTileWithBatchPenTrails]
> +             ifFalse: [next evaluateOn: self]]
> -     [next evaluateOn: self]
>               on: Error do: [:err || newNext |
>                       newNext := scriptEditor tiles at: 1 ifAbsent: [^ self].
>                       newNext = next
>                               ifTrue: [err pass]
>                               ifFalse: [next := newNext].
> +                     self evaluateNextTile]
> +
> + !
> -                     self evaluateNextTile]!
>
> Item was added:
> + ----- Method: EtoysDebugger>>evaluateNextTileWithBatchPenTrails (in category 'evaluating') -----
> + evaluateNextTileWithBatchPenTrails
> +     | penDown |
> +     penDown := self scriptedPlayer getPenDown.
> +     self scriptedPlayer setPenDown: false.
> +     [next evaluateOn: self]
> +             ensure: [self scriptedPlayer setPenDown: penDown].
> +     (penDown and: [next = (scriptEditor tiles at: 1 ifAbsent: [nil])])
> +             ifTrue: [| trailMorph tfm |
> +                     "We've just evaluated the last tile, we should draw pen trail"
> +                     trailMorph := self trailMorph.
> +                     tfm := self scriptedPlayer costume owner transformFrom: trailMorph.
> +                     trailMorph
> +                             drawPenTrailFor: self scriptedPlayer costume
> +                             from: (tfm localPointToGlobal: startingPosition)
> +                             to: (tfm localPointToGlobal: self scriptedPlayerPosition)]!
>
> Item was changed:
>  ----- Method: EtoysDebugger>>initializeWith: (in category 'initialization') -----
>  initializeWith: aScriptEditorMorph
>       scriptEditor := aScriptEditorMorph.
>       next := scriptEditor tiles at: 1 ifAbsent: nil.
> +     self updateStartingPosition;
> +             initialize!
> -     self initialize!
>
> Item was added:
> + ----- Method: EtoysDebugger>>scriptedPlayer (in category 'accessing') -----
> + scriptedPlayer
> +     ^ scriptEditor playerScripted!
>
> Item was added:
> + ----- Method: EtoysDebugger>>scriptedPlayerPosition (in category 'accessing') -----
> + scriptedPlayerPosition
> +     ^ self scriptedPlayer costume
> +             ifNil: [0@0]
> +             ifNotNil: [:m | m referencePosition]!
>
> Item was added:
> + ----- Method: EtoysDebugger>>trailMorph (in category 'accessing') -----
> + trailMorph
> +     ^ self scriptedPlayer costume ifNil: [World] ifNotNil: [:m | m trailMorph]!
>
> Item was added:
> + ----- Method: EtoysDebugger>>updateStartingPosition (in category 'initialization') -----
> + updateStartingPosition
> +     startingPosition := self scriptedPlayerPosition!
>
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> What is the use case for batching pen trials ?

Here's the earliest mention I find of it in my email archive -- from an email from Dan Ingalls, May 25 2000:


> Beginning with the balloon help for that preference (it's in the 'scripting' category;  you have to open a new preferences panel after filing in the file in order to see it)...
>
> "batchPenTrails:
> Ignores the detailed
> movement of pens between
> display updates.  Thus
> multiple line segments
> drawn within a script may
> not be seen individually."
>
> This feature allows you to write scripts such as
>       joe's x := joe's x + vx.
>       joe's y := joe's y + vy.
> and see a smooth resulting line instead of an x-y stairstep.
>
> The downside is that if you happen to write
>       joe forward: 50.
>       joe turn: 45.
>       joe forward: 50.
>       joe turn: 45.
> and run that script, you will neither see 45-degree angles nor sides of length 50.  What it draws is the square formed by the lines from the beginning to the end of the script (ie a square inscribed inside the octagon that you might expect).

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