Exception Caveats and Built-in Exceptions

Exception caveats

Though throwing exceptions is simple, catching them is less so. Using $@ correctly requires us to navigate several subtle risks:

• Unlocalized uses in the same or a nested dynamic scope may modify $@.
• $@ may contain an object that returns a false value in boolean context.
• A signal handler (especially the die signal handler) may change $@.
• The destruction of an object during scope exit may call eval and change $@.