LÖVE

I'm using LOVE version 0.8.0 and when I do something like this
I get an error saying "attempt to call method 'setData' (a nil value)".

Any suggestions? I was thinking it had to do with the fact that newRectangleShape returns PolygonShape rather than Shape.

Welcome to the wonderful world of incomplete documentation! Boolsheet is busting it out like a champ, but there's still a long way to go.

In the meantime, what you want is Fixture:setUserData.

Shape:setData no longer seems to even exist in 0.8.0, despite the docs not saying anything about this as far as I can see. Fixture:setUserData, on the other hand, works more or less as setData used to. So, you can add your data to the corresponding fixture using Fixture:setUserData instead. If you will be using the data in the collision callbacks, the first two parameters to each collision callback are the fixtures in the collision. So, if you have a callback that's something like "addCollision( a, b, coll )" then:
will print out whatever userData you stored in a's fixture.

I got it working using Fixture:setUserData. Thanks!