I think that it should be possible to eliminate World as a global without
hurting performance. The code gets more verbose, but it reduces opportunities
for hidden bugs, so I think it is worth the tradeoff.

I have to admit that the subject of "World global elimination" sounds a bit
ominous, so I decided to put Morphic-dtl.1360 and MorphicExtras-dtl.214 in
the inbox first ;-)

Are there any objections to proceding in this direction? If not I will move
the changes to trunk in day or two.

Dave



On Sat, Nov 11, 2017 at 09:04:49PM +0000, commits at source.squeak.org wrote:
> David T. Lewis uploaded a new version of Morphic to project The Inbox:
> http://source.squeak.org/inbox/Morphic-dtl.1360.mcz
> 
> ==================== Summary ====================
> 
> Name: Morphic-dtl.1360
> Author: dtl
> Time: 11 November 2017, 4:04:34.153784 pm
> UUID: 0e1f3870-5f57-4dc6-a1e7-5d8ce68b71b5
> Ancestors: Morphic-dtl.1359
> 
> World global elimination. Once the current project has been entered, Project current world == World. Begin eliminating references to the global variable World in cases where it is not required.
> 
> =============== Diff against Morphic-dtl.1359 ===============
> 
> Item was changed:
>   ----- Method: ComplexProgressIndicator>>backgroundWorldDisplay (in category 'as yet unclassified') -----
>   backgroundWorldDisplay
>   
>   	self flag: #bob.		"really need a better way to do this"
>   
>   			"World displayWorldSafely."
>   
>   	"ugliness to try to track down a possible error"
>   
>   
> + 	[Project current world displayWorld] ifError: [ :a :b |
> - 	[World displayWorld] ifError: [ :a :b |
>   		| f |
>   		stageCompleted := 999.
>   		f := FileDirectory default fileNamed: 'bob.errors'.
>   		f nextPutAll: a printString,'  ',b printString; cr; cr.
>   		f nextPutAll: 'worlds equal ',(formerWorld == World) printString; cr; cr.
>   		f nextPutAll: thisContext longStack; cr; cr.
>   		f nextPutAll: formerProcess suspendedContext longStack; cr; cr.
>   		f close. Beeper beep.
>   	].
>   !
> 
> Item was changed:
>   ----- Method: Debugger class>>morphicOpenInterrupt:onProcess: (in category '*Morphic-opening') -----
>   morphicOpenInterrupt: aString onProcess: interruptedProcess
>   	"Open a notifier in response to an interrupt. An interrupt occurs when the user types the interrupt key (cmd-. on Macs, ctrl-c or alt-. on other systems) or when the low-space watcher detects that memory is low."
>   	| debugger |
>   	<primitive: 19> "Simulation guard"
>   	debugger := self new.
>   	debugger
>   		process: interruptedProcess
>   		controller: nil
>   		context: interruptedProcess suspendedContext.
>   	debugger externalInterrupt: true.
>   
>   	Preferences logDebuggerStackToFile ifTrue:
>   		[(aString includesSubstring: 'Space') & (aString includesSubstring: 'low')
>   			ifTrue: [Smalltalk logError: aString inContext: debugger interruptedContext to: 'LowSpaceDebug.log']
>   			"logging disabled for 4.3 release, see
>   				http://lists.squeak.org/pipermail/squeak-dev/2011-December/162503.html"
>   			"ifFalse: [Smalltalk logSqueakError: aString inContext: debugger interruptedContext]"].
>   
> + 	Preferences eToyFriendly ifTrue: [Project current world stopRunningAll].
> - 	Preferences eToyFriendly ifTrue: [World stopRunningAll].
>   	^debugger
>   		openNotifierContents: nil label: aString;
>   		yourself
>   !
> 
> Item was changed:
>   ----- Method: Morph>>updateFromResource (in category 'fileIn/out') -----
>   updateFromResource
>   	| pathName newMorph f |
>   	(pathName := self valueOfProperty: #resourceFilePath) ifNil: [^self].
>   	(pathName asLowercase endsWith: '.morph') 
>   		ifTrue: 
>   			[newMorph := (FileStream readOnlyFileNamed: pathName) fileInObjectAndCode.
>   			(newMorph isMorph) 
>   				ifFalse: [^self error: 'Resource not a single morph']]
>   		ifFalse: 
>   			[f := Form fromFileNamed: pathName.
>   			f ifNil: [^self error: 'unrecognized image file format'].
> + 			newMorph := Project current world drawingClass withForm: f].
> - 			newMorph := World drawingClass withForm: f].
>   	newMorph setProperty: #resourceFilePath toValue: pathName.
>   	self owner replaceSubmorph: self by: newMorph!
> 
> Item was changed:
>   ----- Method: MorphHierarchyListMorph>>createContainer (in category 'private') -----
>   createContainer
>   	"Private - Create a container"
>   	| container |
>   	container := BorderedMorph new.
> + 	container extent: (Project current world extent * (1 / 4 @ (2 / 3))) rounded.
> - 	container extent: (World extent * (1 / 4 @ (2 / 3))) rounded.
>   	container layoutPolicy: TableLayout new.
>   	container hResizing: #rigid.
>   	container vResizing: #rigid.
>   	container
>   		setColor: (Color gray: 0.9)
>   		borderWidth: 1
>   		borderColor: Color gray.
>   	container layoutInset: 0.
>   	"container useRoundedCorners."
>   	""
>   	container setProperty: #morphHierarchy toValue: true.
>   	container setNameTo: 'Objects Hierarchy' translated.
>   	""
>   	^ container!
> 
> Item was changed:
>   ----- Method: MorphicProject>>storeSegment (in category 'file in/out') -----
>   storeSegment
>   	"Store my project out on the disk as an ImageSegment.  Keep the outPointers in memory.  Name it <project name>.seg.  *** Caller must be holding (Project alInstances) to keep subprojects from going out. ***"
>   
>   	| is sizeHint |
> + 	(Project current world == world) ifTrue: [^ false]. 
> - 	(World == world) ifTrue: [^ false]. 
>   		"self inform: 'Can''t send the current world out'."
>   	world isInMemory ifFalse: [^ false].  "already done"
>   	world ifNil: [^ false].  world presenter ifNil: [^ false].
>   
>   	ScrapBook default emptyScrapBook.
>   	World checkCurrentHandForObjectToPaste.
>   	world releaseSqueakPages.
>   	sizeHint := self projectParameters at: #segmentSize ifAbsent: [0].
>   
>   	is := ImageSegment
>   			copyFromRootsLocalFileFor: {world presenter. world}	"world, and all Players"
>   			sizeHint: sizeHint.
>   
>   	is state = #tooBig ifTrue: [^ false].
>   	is segment size < 2000 ifTrue: ["debugging" 
>   		Transcript show: self name, ' only ', is segment size printString, 
>   			'bytes in Segment.'; cr].
>   	self projectParameters at: #segmentSize put: is segment size.
>   	is extract; writeToFile: self name.
>   	^ true!
> 
> Item was changed:
>   ----- Method: MorphicProject>>storeSegmentNoFile (in category 'file in/out') -----
>   storeSegmentNoFile
>   	"For testing.  Make an ImageSegment.  Keep the outPointers in memory.  Also useful if you want to enumerate the objects in the segment afterwards (allObjectsDo:)"
>   
>   	| is |
> + 	(Project current world == world) ifTrue: [^ self].		" inform: 'Can''t send the current world out'."
> - 	(World == world) ifTrue: [^ self].		" inform: 'Can''t send the current world out'."
>   	world isInMemory ifFalse: [^ self].  "already done"
>   	world ifNil: [^ self].  world presenter ifNil: [^ self].
>   
>   	"Do this on project enter"
>   	World flapTabs do: [:ft | ft referent adaptToWorld: World].
>   		"Hack to keep the Menu flap from pointing at my project"
>   	"Preferences setPreference: #useGlobalFlaps toValue: false."
>   	"Utilities globalFlapTabsIfAny do:
>   		[:aFlapTab | Utilities removeFlapTab: aFlapTab keepInList: false].
>   	Utilities clobberFlapTabList.	"
>   	"project world deleteAllFlapArtifacts."
>   	"self currentWorld deleteAllFlapArtifacts.	"
>   	ScrapBook default emptyScrapBook.
>   	World checkCurrentHandForObjectToPaste2.
>   
>   	is := ImageSegment
>   			copyFromRootsLocalFileFor: {world presenter. world}	"world, and all Players"
>   			sizeHint: 0.
>   
>   	is segment size < 800 ifTrue: ["debugging" 
>   		Transcript show: self name, ' did not get enough objects'; cr.  ^ Beeper beep].
>   
>   	is extract.
>   	"is instVarAt: 2 put: is segment clone."		"different memory"!
> 
> Item was changed:
>   ----- Method: TheWorldMainDockingBar>>startMessageTally (in category 'menu actions') -----
>   startMessageTally
> + 	| world |
> + 	world := Project current world.
>   	(self confirm: 'MessageTally will start now,
>   and stop when the cursor goes
>   to the top of the screen') ifTrue:
>   		[MessageTally spyOn:
> + 			[[Sensor peekPosition y > 0] whileTrue: [world doOneCycle]]]!
> - 			[[Sensor peekPosition y > 0] whileTrue: [World doOneCycle]]]!
> 
> Item was changed:
>   ----- Method: TheWorldMenu>>startMessageTally (in category 'commands') -----
>   startMessageTally
> + 	| world |
> + 	world := Project current world.
> - 
>   	(self confirm: 'MessageTally will start now,
>   and stop when the cursor goes
>   to the top of the screen') ifTrue:
>   		[MessageTally spyOn:
> + 			[[Sensor peekPosition y > 0] whileTrue: [world doOneCycle]]]!
> - 			[[Sensor peekPosition y > 0] whileTrue: [World doOneCycle]]]!
> 
>