in reply to Re^2: print statement changes results!
in thread print statement changes results!

The values return from $-[0]/$+[0] are integers stored in the IV part of the scalar.

Interpolating them in the print statement will have the side effect of forcing the PV slots to be populated with the stringified versions of those integers.

If the XS code that is behind this VShape object is only looking at the PV slot, that would explain why the print statement has the effect of making the code work.

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