10.14.6 Debugging tips

A few questions to ask yourself when working with pure properties:

• Is the property really pure? Are you sure that its value could not be changed later in the compiling process due to other changes?
• Can the property be made to correspond even more exactly with the eventual impure property?
• For a spanner, is the pure property changing correctly depending on the starting and ending points of the spanner?
• For an Item, will the item’s pure height need to act in horizontal spacing but not in vertical spacing? If so, use extra-spacing-height instead of pure height.