SWI-Prolog -- prolog:message

Documentation
- Reference manual
  - Built-in Predicates
    - Printing messages
- Packages

[nondet]prolog:message_action(+Term, +Kind)

This hook is called before message_hook/3 as below. This hook appeared in 9.3.34. It allows to associate side-effects with messages in a reliable way by decoupling printing (or reporting some other way) from associated side effects. See also broadcast/1 from library library(broadcast).

    forall(prolog:message_action(Term, Kind), true).