Debugging possible bug

Niko Schwarz niko.schwarz at gmx.net
Sun Jan 5 13:06:56 UTC 2003


Hello,
I was just just exploring the exolab jabber protocol when my debugger became 
unable to display instance variable whose value was "nil".
I got instead: <error in printString: evaluate "inputQ printString" to debug>

A little debugging revealed something I did not quite understand: 

The stack trace was this:
JabberXMLReader(ProtoObject)>>doesNotUnderstand:
Inspector>>selection
Inspector>>addCollectionItemsTo:
Inspector>>fieldListMenu:
PluggableListMorph(ScrollPane)>>getMenu:
PluggableListMorph>>getMenu:
PluggableListMorph(ScrollPane)>>yellowButtonActivity:
PluggableListMorph>>mouseDown:
PluggableListMorph(Morph)>>handleMouseDown:
MouseButtonEvent>>sentTo:
[snap]

The error occured in:
 selection
	"The receiver has a list of variables of its inspected object. 
	One of these is selected. Answer the value of the selected variable."
	| basicIndex |
	selectionIndex = 0
		ifTrue: [^ ''].
	selectionIndex = 1
		ifTrue: [^ object].
	selectionIndex = 2
		ifTrue: [^ object longPrintString].
	selectionIndex - 2 <= object class instSize
		ifTrue: [^ object instVarAt: selectionIndex - 2].      "<----- there, 
because object is nil"

The funny thing: evaluating selectionIndex = 0 results to true.
selectionIndex is assigned nowhere in there, so I suppose this is a bug, not?

regards,

nick
-- 
Accident, n.:
	A condition in which presence of mind is good, but absence of
body is better.




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