Hi Paul, You can set the object to be "read only" (aka "immutable") and handle the exception.
E.g. | u | u := User named: 'Paul'. u beReadOnlyObject. [ "your code modifying u's state" ] on: ModificationForbidden do: [ :ex | ex halt. "inspect state" u beWritableObject. ex resume ]. Probably there is a better way to do this with slots, using default ones or subclassing `InstanceVariableSlot` for that instance only and halting on the `write:to:` method of it. Regards, Esteban A. Maringolo El mié., 2 ene. 2019 a las 15:45, PAUL DEBRUICKER via Pharo-users (< pharo-users@lists.pharo.org>) escribió: > Hi - > > Is there a way to haltOnChange or some such for an object? > > > I have an instance that gets into a state I don't understand and would > like to watch it or several of its inst vars for when they change. > > I could set a lot of #haltIf: statements and step through but hope someone > has a better strategy > > > thanks & happy new year. > > > Paul >