[squeak-dev] The Inbox: System-dtl.981.mcz

David T. Lewis lewis at mail.msen.com
Thu Dec 7 03:11:58 UTC 2017

This is an extension of Marcel's tryOtherProjectForRecovery: mechanism.

My working image has many Morphic projects, and a few MVC projects, but in
general the Morphic projects do not have an MVC project as a parent project.

This change allows a fatal error in the UI for any of the Morphic projects
to find any available MVC project and use it for error recovery.

For example, if I am in a Mophic project and I comment out the implementation
of Morph>>bounds, this leads to a fatal error. Normally this would have dropped
into an emergency evaluator. With this change, we instead enter an MVC project
with a debugger on the failure that occurred in the Morphic UI.


On Thu, Dec 07, 2017 at 02:52:28AM +0000, commits at source.squeak.org wrote:
> David T. Lewis uploaded a new version of System to project The Inbox:
> http://source.squeak.org/inbox/System-dtl.981.mcz
> ==================== Summary ====================
> Name: System-dtl.981
> Author: dtl
> Time: 6 December 2017, 9:52:13.947225 pm
> UUID: d00b5ac2-0e56-40d3-91d6-7803be283e1c
> Ancestors: System-mt.980
> For emergency evaluator handling, Project class>>handlePrimitiveError: will first try to find a parent project of different type (e.g. MVC if current project is Morphic, or vice versa). If found, the other project is opened, and the error is handled there. If no such project is found, then the traditional emergency evaluator transcript is opened.
> Extend this strategy by first checking parent project types, and if not successful search all projects to find any project of different type.
> A typical scenario is the case of an image with many Morphic projects, and one MVC project anywhere in the project hierarchy. In the event of an unrecoverable error in any of the Morphic projects, the MVC project will be identified as the project for emergency recovery. This permits an MVC debugger to be used to recover from the error condition, after which the failed Morphic user interface can be reentered.
> =============== Diff against System-mt.980 ===============
> Item was changed:
>   ----- Method: Project class>>tryOtherProjectForRecovery: (in category 'error recovery') -----
>   tryOtherProjectForRecovery: errorMessage
>   	"Try entering the parent project if it uses a different user interface. We determine this by comparing the project's class."
>   	| safeProject nextProject |
>   	nextProject := Project current.
>   	safeProject := nil.
>   	[safeProject notNil or: [nextProject isTopProject]] whileFalse: [
>   		nextProject := nextProject parent.
>   		(Project current isKindOf: nextProject class)
>   			ifFalse: [safeProject := nextProject]].
> + 
> + 	"Parent project was not of a different type. Search through all known
> + 	projects to find any one that is of different project type."
> + 	safeProject ifNil: [
> + 		Smalltalk garbageCollect.
> + 		safeProject := Project allSubInstances
> + 			detect: [ :proj | proj class ~= Project
> + 				or: [ (proj isKindOf: Project current class) not ] ]
> + 			ifNone: [ nil ] ].
> + 
>   	safeProject ifNotNil: [:p | 
>   		p enterForEmergencyRecovery.
>   		"Active process will usually suspend after this."].!

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