[squeak-dev] Circular definitions of size and do:

Rodney Polkinghorne rpolkinghorne at groupwise.swin.edu.au
Fri Sep 30 02:22:17 UTC 2011

Dear list

I wanted an array that lazily initialized elements 1 to n when you
asked for the nth one.  So I ran something like:

SequenceableCollection variableSubclass #Foo ...

When I started a workspace, and tried Foo new: 10, my image hung.

Eventually, I found the problem.  The workspace tried to print the
answered instance, which resulted in it being sent a do: message to
print its elements.  This ran the method

SequenceableCollection>>do: aBlock
	1 to: self size do:
		[:index | aBlock value: (self at: index)]

which ran

	| tally |
	tally := 0.
	self do: [:each | tally := tally + 1].
	^ tally

which sent do:, which sent size, which ...

Is this considered a bug, or a learning experience for new players?
ArrayedCollection avoids it by restoring the primitive method for


More information about the Squeak-dev mailing list