Or you can repro from a fresh 6.1 if you follow the exercism Pharo instructions (https://exercism.io/tracks/pharo) to load the first hello world-world example and run the tests. This has my code changes to make create work with a nil class - but maybe we can do better?

Sent from my iPhone

On 17 Aug 2018, at 06:21, Marcus Denker <marcus.denker@inria.fr> wrote:

On 10 Aug 2018, at 23:16, Tim Mackinnon <tim@testit.works> wrote:

Actually I think I figured that bit out - a bit clumsily - (pointers appreciated)

createMissingClassActionFor: aMessage in: aContext
|errorNode senderContext newClass variableNode |
senderContext := aContext sender.
errorNode := senderContext method sourceNodeExecutedForPC: senderContext pc.
variableNode := errorNode receiver receiver.

newClass := OCUndeclaredVariableWarning new node: variableNode; defineClass: variableNode name.
aContext restart.

However that last line is wrong, as it doesn��t restart with my newly defined class - I also tried

aContext restartWithNewReceiver: newClass

But again, I get a debugger where my class is still bound to nil. So what��s the trick to re-evaluate with the new class I��ve created? Or maybe I��m totally on the wrong track (still its very interesting��)

what is a bit bad is that you catch the problem ��too late�� (that is, the DNU to nil, not the read of nil), so nil is already pushed on the stack at this point.

I tried it in the inspector and at least the class binding was correct after defining the class�� do you have an image with the whole code to try?

Marcus