menu_book Course Curriculum (Smalltalk Complete Course) expand_more
on:do:
Learn on:do: in Smalltalk with a construct-specific explanation, a unique example, a practical boundary, and a mastery check.
on:do: is an atomic Smalltalk topic inside Exceptions & Resources. The example below uses the actual construct named by the lesson rather than a generic placeholder.
Focus on what on:do: changes: the input, binding, control path, object state, collection, runtime effect, or language contract. Then alter one value and verify that the behavior changes for a reason specific to this feature.
Topic-specific example
[ 1 / 0 ] on: ZeroDivide do: [ :ex | #divisionError ].
Change the key input in this Smalltalk example and predict the result first; the named construct should be the reason the behavior changes.