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list-traps can be used to print a description of all known trap objects. This uses a weak value hash table, keyed by a trap index number. Each trap object has its index number assigned, and is added to the hash table, when it is created by a make trap-class ... call. When a trap object is GC'd, it is automatically removed from the hash table, and so no longer appears in the output from list-traps.

— Variable: all-traps

Weak value hash table containing all known trap objects.

— Procedure: list-traps

Print a description of all known trap objects.

The following example shows a single trap that traces applications of the procedure facti.

     guile> (list-traps)
     #<<procedure-trap> 100d2e30> is an instance of class <procedure-trap>
     Slots are:
          number = 1
          installed = #t
          condition = #f
          skip-count = 0
          single-shot = #f
          behaviour = (#<procedure trace-trap (trap-context)>)
          repeat-identical-behaviour = #f
          procedure = #<procedure facti (n a)>

When all-traps or list-traps reveals a trap that you want to modify but no longer have a reference to, you can retrieve the trap object by calling get-trap with the trap's number. For example, here's how you could change the behaviour of the trap listed just above.

     (slot-set! (get-trap 1) 'behaviour (list debug-trap))
— Procedure: get-trap number

Return the trap object with the specified number, or #f if there isn't one.